Humanised anti kallikrein-2 antibody

ABSTRACT

The present invention provides antibody polypeptides with binding specificity for human kallikrein-2 (hK2), wherein the antibody polypeptide comprises (a) a heavy chain variable region comprising the amino acid sequences of SEQ ID NO: 1 and SEQ ID NO: 2 and SEQ ID NO: 3 and/or (b) a light chain variable region comprising the amino acid sequences of SEQ ID NO: 4 and SEQ ID NO: 5 and SEQ ID NO: 6, and wherein the heavy chain variable region and light chain variable region comprise framework amino acid sequences from one or more human antibodies. The invention further provides use of said antibody polypeptides in the diagnosis and treatment of prostate cancer.

This application is a § 371 application of PCT/GB2014/053420, filed Nov.19, 2014, which in turn claims priority to GB Application 1320408.6,filed Nov. 19, 2013, and GB Application 1401973.1, filed Feb. 5, 2014.The entire disclosure of each of the foregoing applications isincorporated by reference herein.

FIELD OF THE INVENTION

This invention pertains in general to the field of therapeutic anddiagnostic agents and methods, particularly in field of prostate cancer.

BACKGROUND

Prostate cancer is at the present time the most common form of canceramong men. The prostate is a walnut-sized gland in men that producesfluid that is a component in semen. The prostate has two or more lobes,or sections, enclosed by an outer layer of tissue. The prostate islocated in front of the rectum and just below the urine bladder, andsurrounds the urethra.

The occurrence of prostate cancer is highest in the northwestern part ofEurope and in the United States. The growth of the tumour is usually aprocess that takes place during a long period of time. Prostate canceris normally a mild form of cancer. In fact, the majority of mendiagnosed with prostate cancer survive and recover, with only a minorityof the men encountering a more aggressive form of prostate cancer, whichmetastasizes in an early stage. This aggressive form of prostate cancermay only be curable if it is diagnosed at an early stage, before thecancer has spread to extracapsular tissue.

Today, diagnosis and monitoring of prostate cancer is typicallyperformed by measuring the concentration of a prostate specific antigen(PSA) in the blood of the patient. If the concentration of PSA ismarkedly high in several consecutive measurements, performed atdifferent points of time, the assessment is that there is a probabilityof prostate cancer. At this point of time a biopsy may be performed toverify prostate cancer.

PSA (also known as kallikrein III) is a protein, constituted of a singlechain of 237 amino acids, which is produced in the secretory cells ofthe prostate. These secretory cells may be found in the whole prostategland. PSA is well established and thoroughly researched marker inrespect of prostate cancer. By comparison with healthy cells theproduction of PSA is lower in malignant cells and higher in hyperplasticcells. It is rather contradictory that in fact the concentration of PSAis higher in blood from men suffering from prostate cancer. However, oneexplanation may be that the malignant cells have a deteriorated cellstructure, and are therefore more permeable to PSA.

Another important serine protease suitable as a target for therapy ofprostate cancer is human glandular kallikrein 2 (hK2). The gene codinghK2 is located on chromosome 19, together with the gene coding for PSA.hK2 is expressed mainly in the prostate tissue, just as PSA. In theprostate, PSA is present as an inactive pro-form and is activatedthrough the peptidase action of hK2. Immunohistochemical research inrespect of hK2 has shown that hK2 is expressed in relation to the levelof differentiation. This means that hK2 is expressed in a higher yieldin tissue of low differentiation, such as tissue subjected to prostatecancer, and in a lower yield in tissue of high differentiation, such astissue subjected to benign prostatic hyperplasia (BPH) which is anothercommon prostate problem.

Today's therapies of prostate cancer are surgery (e.g., radicalprostatectomy), radiation therapy (including, brachytherapy and externalbeam radiation therapy, high-intensity focused ultrasound (HIFU),chemotherapy, oral chemotherapeutic drugs, cryosurgery (freezing thetumor), hormonal therapy (such as antiandrogen therapy), castration orcombinations of the foregoing.

Most of these therapies (surgery and external radiation therapy) are,however, only (or primarily) useful for treatment of primary tumours andlarge metastases. Chemotherapy is used for disseminated of the cancerbut for most of these patients, it is a palliative effect and/orprolonged survival. Other or complementary treatment modalities aretherefore necessary to achieve considerable improvements of thedisseminated malignant diseases, particular in cases of micrometastases.

Therapy, such as immunotherapy or radioimmunotherapy, using targetingmolecules such as antibodies and fragments could give the possibility oftherapy of disseminated disease.

Thus, there is a need for a new therapeutic agents and methods fortreating and diagnosing prostate cancer.

SUMMARY OF THE INVENTION

Accordingly, the present invention seeks to mitigate, alleviate oreliminate one or more of the above-identified deficiencies in the artand disadvantages singly or in any combination and solves at least theabove mentioned problems by providing a therapeutic agents and methodsaccording to the appended patent claims.

A first aspect of the present invention provides an antibody polypeptidewith binding specificity for human kallikrein-2 (hK2), wherein theantibody polypeptide comprises

-   (a) a heavy chain variable region comprising the amino acid    sequences of SEQ ID NO:1 and SEQ ID NO:2 and SEQ ID NO:3

CDRH1: SEQ ID NO: 1 SDYAWN CDRH2: SEQ ID NO: 2 YISYSGSTTYNPSLKS CDRH3:SEQ ID NO: 3 GYYYGSGFand/or

-   (b) a light chain variable region comprising the amino acid    sequences of SEQ ID NO:4 and SEQ ID NO:5 and SEQ ID NO:6

CDRL1: SEQ ID NO: 4 KASESVEYFGTSLMH CDRL2: SEQ ID NO: 5 AASNRES CDRL3:SEQ ID NO: 6 QQTRKVPYTand wherein the heavy chain variable region and light chain variableregion comprise framework amino acid sequences from one or more humanantibodies.

The above six amino acid sequences represent thecomplementarity-determining regions (CDRs) of the antibody polypeptidesof the invention, as defined according to Kabat et al., (1991) Sequencesof Immunological Interest, 5th edition, NIH, Bethesda, Md. (thedisclosures of which are incorporated herein by reference).

By “antibody polypeptide” we include substantially intact antibodymolecules, single chain antibodies, diabodies, bispecific antibodies,antibody heavy chains, antibody light chains, homodimers andheterodimers of antibody heavy and/or light chains, as well as antigenbinding fragments and derivatives of the same.

The term “amino acid” as used herein includes the standard twentygenetically-encoded amino acids and their corresponding stereoisomers inthe ‘D’ form (as compared to the natural I′ form), omega-amino acidsother naturally-occurring amino acids, unconventional amino acids (e.g.α,α-disubstituted amino acids, N-alkyl amino acids, etc.) and chemicallyderivatised amino acids (see below).

When an amino acid is being specifically enumerated, such as “alanine”or “Ala” or “A”, the term refers to both L-alanine and D-alanine unlessexplicitly stated otherwise. Other unconventional amino acids may alsobe suitable components for polypeptides of the present invention, aslong as the desired functional property is retained by the polypeptide.For the peptides shown, each encoded amino acid residue, whereappropriate, is represented by a single letter designation,corresponding to the trivial name of the conventional amino acid.

In one embodiment, the polypeptides as defined herein comprise orconsist of L-amino acids.

The antibody polypeptides of the invention exhibit specificity for hK2.

An exemplary hK2 sequence is described as Transcript: KLK2-201(ENST00000325321), a product of gene ENSG00000167751, as given in theensemble database which can be found at the following world-wide-webaddress at:

-   -   ensembl.org/Homo_sapiens/Transcript/Sequence_Protein?g=ENSG00000167751;        r=19:51376689-51383822; t=ENST00000325321        and has the following sequence:

[SEQ ID NO: 7] MWDLVLSIAL SVGCTGAVPL IQSRIVGGWE CEKHSQPWQVAVYSHGWAHC GGVLVHPQWV LTAAHCLKKN SQVWLGRHNLFEPEDTGQRV PVSHSFPHPL YNMSLLKHQS LRPDEDSSHDLMLLRLSEPA KITDVVKVLG LPTQEPALGT TCYASGWGSIEPEEFLRPRS LQCVSLHLLS NDMCARAYSE KVTEFMLCAGLWTGGKDTCG GDSGGPLVCN GVLQGITSWG PEPCALPEKP AVYTKVVHYR KWIKDTIAANP(wherein the sequence of the mature, active hK2 protein is underlined,which is preceded at its N-terminus by a signal peptide and propeptidesequence)

Most of the hK2 found in seminal plasma is inactive and complexed withprotein C inhibitor (PCI). It is also possible that hK2 forms complexeswith other extracellular protease inhibitors. In vitro studies show thathK2 may bind to α2-antiplasmin (α2-AP), ACT, AMG, anti-thrombin III(ATIII), C1-inactivator and plasminogen activator inhibitor-1 (PAI-1).

In one embodiment, the antibody polypeptide has specificity for the free(that is, non-complexed) isoform of hK2 compared to the complexedisoform of hK2. Binding moieties with specificity for the free isoformof hK2 may have binding specificity for an epitope that is exposed onthe free isoform of hK2, but is unexposed on the complexed isoform ofhK2, and this may be a linear or a conformational (that is, non-linear)epitope. For example, the antibody polypeptide may have specificity foran epitope that includes one or more amino acid residues that are partof the catalytic cleft of hK2 that is exposed in free hK2 and unexposedin a complexed isoform, such as the form present in seminal fluid whenhK2 is complexed to PCI. Epitope mapping of hK2 is described in Väisänenet al, Clinical Chemistry 50:9, 1607-1617 (2004), the disclosures ofwhich are incorporated herein by reference.

Further examples of hK2 proteins are identified by the followingaccession numbers:

-   -   (a) GenBank: AAF08277.1;    -   (b) GenBank: AAF08275.1; and    -   (c) UniProtKB/Swiss-Prot: P20151.1

The production of recombinant hK2 is described in Lovgren et al., 1999,Eur. J. Biochem. 266:1050-5 (the disclosures of which are incorporatedherein by reference).

By “specificity” we mean that the antibody polypeptide is capable ofbinding to hK2 in vivo, i.e. under the physiological conditions in whichhK2 exists within the human body. Preferably, the antibody polypeptidedoes not bind to any other protein in vivo.

Such binding specificity may be determined by methods well known in theart, such as ELISA, immunohistochemistry, immunoprecipitation, Westernblots and flow cytometry using transfected cells expressing hK2.Advantageously, the antibody polypeptide is capable of bindingselectively to hK2, i.e. it bind at least 10-fold more strongly to hK2than to another proteins (in particular, other kallikreins such asprostate specific antigen or PSA). Preferably, the antigen polypeptidedoes not bind PSA in vivo.

Murine antibodies with specificity for hK2 are known in the art. Forexample, Väisänen et al., 2004, Clinical Chemistry 50(9):1607-1617describes the production of monoclonal antibodies in mice withspecificity for hK2 (the disclosures of which are incorporated herein byreference). Two of the antibodies, designated “11B6” and “7D7”, arestated to be selective for hK2.

The amino acid sequences of the component heavy and light chains of themurine antibody 11B6 are disclosed in International Patent ApplicationNo. PCT/GB2012/052675 (WO 2013/061083; the disclosures of which areincorporated herein by reference in their entirety); see, in particular,SEQ ID NOs: 4 and 5 therein.

The antibody polypeptides of the present invention are based on aselected humanised version of the 11B6 antibody, which exhibitsunexpected favourable properties.

In particular, the humanised antibodies of the invention exhibit anenhanced therapeutic ratio compared to the parent murine 11B6 antibody(m11B6) from which their CDR sequences were derived (see Example 6).

By “enhanced therapeutic ratio” we mean that the antibody polypeptide ofthe invention (a humanised form of the 11B6 antibody), when administeredto a patient with a prostate tumour, provides a higher ratio of tumourabsorbed dose to (healthy) bone marrow absorbed dose than the parentmurine 11B6 antibody (compared at the same radioactivity andadministration route). The ratio of tumour to bone marrow absorbed dosesmay be calculated using the method described in Example 6.

The unexpectedly better therapeutic profile of the antibodies of theinvention permits higher radiation doses (absorbed doses) to be used,leading to greater efficacy in the treatment of prostate cancer withoutincreasing side-effects or ‘collateral damage’ to healthy tissues andorgans.

Humanisation (also called reshaping or CDR-grafting) is a technique forreducing the immunogenicity of monoclonal antibodies from xenogeneicsources (commonly, from rodents such as mice) and for improving theiractivation of the human immune system (see review by Almagro & Fransson,2008, Frontiers in Bioscience 13:1619-1633; the disclosures of which areincorporated herein by reference). There are several humanisedmonoclonal antibodies in clinical trials and a few have been givenapproval to be used as drugs. Although the mechanics of producing theengineered monoclonal antibody using the techniques of molecular biologyare relatively straightforward, simple grafting of the rodentcomplementarity-determining regions (CDRs) into human frameworks doesnot always reconstitute the binding affinity and specificity of theoriginal monoclonal antibody. In order to humanize an antibody, thedesign of the humanised antibody is a critical step in reproducing thefunction of the original molecule.

The design of a humanised antibody includes several key choices,including the extents of the CDRs to be used and the human frameworks tobe used. However, in order to retain the specificity of the parentantibody, it may also be critical to substitute one or more residuesfrom the rodent mAb into the human framework regions (so-calledbackmutations). Identifying the position of the necessary backmutationsrequires a detailed sequence/structural analysis. Recently, phagelibraries have been used to vary the amino acids at chosen positions.Similarly, many approaches have been used to choose the most appropriatehuman frameworks in which to graft the rodent CDRs. Early experimentsused a limited subset of well-characterised human monoclonal antibodies(often where the structure was available), irrespective of the sequenceidentity to the rodent monoclonal antibody (the so-called fixedframeworks approach). Some groups use variable regions with high aminoacid sequence identity to the rodent variable regions (homology matchingor best-fit); others use consensus or germline sequences while stillothers select fragments of the framework sequences within each light orheavy chain variable region from several different human monoclonalantibodies. There are also approaches to humanisation developed whichreplace the surface rodent residues with the most common residues foundin human monoclonal antibodies (“resurfacing” or “veneering”) and thosewhich use differing definitions of the extents of the CDRs.

However, despite extensive study of antibody humanisation, some rodentmonoclonal antibodies have proved difficult to humanise.

Development of the antibody polypeptides of the invention requiredbackmutations not only in the framework regions but also in some of theCDRs (see Example 1 below). Thus, the six CDR sequences representedabove in SEQ ID NOS: 1 to 6 are derived from the murine anti-hK2antibody 11B6, but contain mutations in CDRH2 (SEQ ID NO: 2) and CDRL1(SEQ ID NO: 4) relative to the parent murine antibody. These mutationsin the CDRs were made in order to confer optimal specificity andstability on the humanised version of 11B6.

In one embodiment, the antibody polypeptides of the invention bind hK2with a K_(D) of greater than 0.1×10⁻⁹ M.

Methods for measuring the overall affinity (K_(D)) and on-rate (ka) andoff-rate (kd) of an interaction (such as an interaction between anantibody and a ligand) are well known in the art. Exemplary in vitromethods are described in Example 3 below. It is also conceivable to useflow cytometry based methods (Sklar et al., 2002, Annu Rev BiophysBiomol Struct, 31:97-119; the disclosures of which are incorporatedherein by reference).

Advantageously, the antibody polypeptide of the invention has anaffinity (K_(D)) for hK2 of lower than 1.0×10⁻¹⁰ M, for example a K_(D)lower than 9.0×10⁻¹¹ M, 8.0×10⁻¹¹ M, 7.0×10⁻¹¹ M, 6.0×10⁻¹¹ M, 5.0×10⁻¹¹M, 4.0×10⁻¹¹ M, 3.0×10⁻¹¹ M, 2.0×10⁻¹¹ M or lower than 1.0×10⁻¹¹ M.

It will be appreciated by persons skilled in the art that the antibodypolypeptides of the invention may constitute antibody heavy chains,antibody light chains, homodimers and heterodimers of antibody heavyand/or light chains, and antigen binding fragments and derivatives ofthe same.

In one embodiment, the antibody polypeptide comprises or consists of anintact (i.e. complete) antibody, such as an IgA, IgD, IgE, IgG or IgMmolecule.

Advantageously, the antibody polypeptide comprises or consists of anintact IgG molecule, or an antigen-binding fragment or derivative of thesame.

The IgG molecule may be of any known subtype, for example IgG1, IgG2,IgG3 or IgG4.

By “antigen-binding fragments and derivatives” of antibodies we includeFv fragments (e.g. single chain Fv and disulphide-bonded Fv), Fab-likefragments (e.g. Fab fragments, Fab′ fragments and F(ab)₂ fragments) anddomain antibodies (e.g. single V_(H) variable domains or V_(L) variabledomains).

For example, the antibody polypeptide may comprise or consist of an scFvor Fab fragment.

A further characterising feature of the antibody polypeptides of thepresent invention is the presence of framework amino acid sequences fromone or more human antibodies in the heavy and light chain variableregions.

By “framework sequences” we include the regions of the heavy and lightchain variable domains other than the CDRs. Typically, each variabledomain will comprise four framework regions, designated FR1 to FR4,within which the CDR sequences are located:FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4

It will be appreciated that the amino acid sequences of the frameworkregions may be fully human or may contain one or more backmutations(i.e. the amino acid sequence present in the human framework may besubstituted with the amino acid found at the corresponding positionwithin the parent rodent variable domain from which the CDRs arederived). Consequently, the sequences of FR1, FR2, FR3 and/or FR4 of theheavy and/or light chain variable domain(s) of the antibody polypeptideof the invention may be non-naturally occurring.

In one embodiment, the framework sequences of the antibody polypeptideshare at least 70% sequence identity with framework regions from one ormore human antibodies, for example at least 80%, 85%, 90%, 95%, 96%,97%, 98%, 99% or more. Thus, the antibody polypeptide may comprise aheavy chain FR1 region that shares least 70% sequence identity with anFR1 region of a human antibody. It will be appreciated, however, thatthe heavy and light chains of the antibody polypeptide may sharesequence identity with the framework regions of different humanantibodies.

Percent identity can be determined by, for example, the LALIGN program(Huang and Miller, Adv. Appl. Math. (1991) 12:337-357) at the Expasyfacility site (http://www.ch.embnet.org/software/LALIGN_form.html) usingas parameters the global alignment option, scoring matrix BLOSUM62,opening gap penalty −14, extending gap penalty −4. Alternatively, thepercent sequence identity between two polypeptides may be determinedusing suitable computer programs, for example the GAP program of theUniversity of Wisconsin Genetic Computing Group and it will beappreciated that percent identity is calculated in relation topolypeptides whose sequence has been aligned optimally.

The alignment may alternatively be carried out using the Clustal Wprogram (as described in Thompson et al., 1994, Nucl. Acid Res.22:4673-4680, which is incorporated herein by reference). The parametersused may be as follows:

-   -   Fast pair-wise alignment parameters: K-tuple(word) size; 1,        window size; 5, gap penalty; 3, number of top diagonals; 5.        Scoring method: x percent.    -   Multiple alignment parameters: gap open penalty; 10, gap        extension penalty; 0.05.    -   Scoring matrix: BLOSUM.

Alternatively, the BESTFIT program may be used to determine localsequence alignments.

In one embodiment, the framework sequences of the heavy variable domainof the antibody polypeptide of the invention are encoded by the humanimmunoglobulin VH4 gene family.

For example, the framework sequences may be encoded, at least in part,by a VH4-28 germline gene (e.g. FR1, FR2 and FR3 may be encoded byVH4-28 and FR4 may be encoded by JH1).

Thus, in one embodiment, the antibody polypeptide may comprise orconsist of a heavy chain variable region which comprises or consists ofthe amino acid sequence of SEQ ID NO:8:

[SEQ ID NO: 8] QVQLQESGPGLVKPSDTLSLTCAVSGNSITSDYAWNWIRQPPGKGLEWIGYISYSGSTTYNPSLKSRVTMSRDTSKNQFSLKLSSVTAVDTAVYYCATGYYYGSGFWGQGTLVTVSS

In one embodiment, the framework sequences of the light variable domainof the antibody polypeptide of the invention are encoded by the humanimmunoglobulin Kappa V4 gene family.

For example, the framework sequences may be encoded, at least in part,by an IgkV4-B3 germline gene (e.g. FR1, FR2 and FR3 may be encoded byIgkV4-B3 and FR4 may be encoded by JK2).

Thus, in one embodiment, the antibody polypeptide may comprise orconsist of a light chain variable region which comprises or consists ofthe amino acid sequence of SEQ ID NO: 9:

[SEQ ID NO: 9] DIVLTQSPDSLAVSLGERATINCIKASESVEYFGTSLMHWYQQKPGQPPKLLIYAASNRESGVPDRFSGSGSGTDFTLTISSLQAEDVAV YYCQQTRKVPYTFGQGTKLEIK

By “at least in part” we include that the framework sequences compriseat least ten contiguous amino acids encoded by the reference gene, forexample at least 20 contiguous amino acids. We also include that one ormore, but not all, the FR regions are encoded by the reference gene (forexample, FR1 and FR2 may be encoded by the reference gene, but not FR3).

In a preferred embodiment, the antibody polypeptide comprises a heavychain variable region which comprises or consists of the amino acidsequence of SEQ ID NO:8 and a light chain variable region whichcomprises or consists of the amino acid sequence of SEQ ID NO: 9.

Optionally, the antibody polypeptide of the invention further comprisesa heavy chain constant region, or part thereof.

In one embodiment, the antibody polypeptide comprises a CH1, CH2 and/orCH3 region of an IgG heavy chain (such as an IgG1, IgG2, IgG3 or IgG4heavy chain). Thus, the antibody polypeptide may comprise part or all ofthe constant regions from an IgG1 heavy chain. For example, the antibodypolypeptide may be a Fab fragment comprising CH1 and CL constantregions.

In one embodiment, the antibody polypeptide may comprise an antibodyFc-region. It will be appreciated by a skilled person that the Fcportion may be from an IgG antibody, or from a different class ofantibody (such as IgM, IgA, IgD or IgE). In one embodiment, the Fcregion is from an IgG1, IgG2, IgG3 or IgG4 antibody.

The Fc region may be naturally-occurring (e.g. part of an endogenouslyproduced antibody) or may be artificial (e.g. comprising one or morepoint mutations relative to a naturally-occurring Fc region and/ormodifications to the carbohydrate moieties within the CH2 domain).Fc-regions with point mutations improving their ability to bind FcR maybe advantageous, e.g. by altering serum half life or by modulating (i.e.enhancing or reducing) binding to Fcγ receptors (FcγR) involved in ADCCand CDC.

Advantageously, the antibody polypeptide may comprise the amino acidsequence of SEQ ID NO: 10, or part thereof:

[SEQ ID NO: 10] A S T K G P S V F P L A P S S K S T S G G TA A L G C L V K D Y F P E P V T V S W N S GA L T S G V H T F P A V L Q S S G L Y S L SS V V T V P S S S L G T Q T Y I C N V N H KP S N T K V D K K V E P K S C D K T H T C PP C P A P E L L G G P S V F L F P P K P K DT L M I S R T P E V T C V V V D V S H E D PE V K F N W Y V D G V E V H N A K T K P R EE Q Y N S T Y R V V S V L T V L H Q D W L NG K E Y K C K V S N K A L P A P I E K T I SK A K G Q P R E P Q V Y T L P P S R E E M TK N Q V S L T C L V K G F Y P S D I A V E WE S N G Q P E N N Y K T T P P V L D S D G SF F L Y S K L T V D K S R W Q Q G N V F S CS V M H E A L H N H Y T Q K S L S L S P G K

Optionally, the antibody polypeptide of the invention further comprisesa light chain constant region, or part thereof.

In one embodiment, the antibody polypeptide comprises a CL region of anIgG light chain (such as a kappa or lambda light chain)

For example, the antibody polypeptide may comprise the amino acidsequence of SEQ ID NO: 11, or part thereof:

[SEQ ID NO: 11] R T V A A P S V F I F P P S D E Q L K S G TA S V V C L L N N F Y P R E A K V Q W K V DN A L Q S G N S Q E S V T E Q D S K D S T YS L S S T L T L S K A D Y E K H K V Y A C EV T H Q G L S S P V T K S F N R G E C

Advantageously, the antibody polypeptide comprises a heavy chainconstant region which comprises or consists of the amino acid sequenceof SEQ ID NO: 10 and a light chain constant region which comprises orconsists of the amino acid sequence of SEQ ID NO: 11.

In one preferred embodiment, the antibody polypeptide of the inventioncomprises:

-   (a) a heavy chain which comprises or consists of the amino acid    sequence of SEQ ID NO: 12 (wherein the variable region is in bold    and the CDR sequences are in boxed italics)

[SEQ ID NO: 12] Q V Q L Q E S G P G L V K P S D T L S

N Q F S L K L S S V T A V D T A V Y Y

V S S A S T K G P S V F P L A P S S KS T S G G T A A L G C L V K D Y F P EP V T V S W N S G A L T S G V H T F PA V L Q S S G L Y S L S S V V T V P SS S L G T Q T Y I C N V N H K P S N TK V D K K V E P K S C D K T H T C P PC P A P E L L G G P S V F L F P P K PK D T L M I S R T P E V T C V V V D VS H E D P E V K F N W Y V D G V E V HN A K T K P R E E Q Y N S T Y R V V SV L T V L H Q D W L N G K E Y K C K VS N K A L P A P I E K T I S K A K G QP R E P Q V Y T L P P S R E E M T K NQ V S L T C L V K G F Y P S D I A V EW E S N G Q P E N N Y K T T P P V L DS D G S F F L Y S K L T V D K S R W QQ G N V F S C S V M H E A L H N H Y T Q K S L S L S P G Kand/or

-   (b) a light chain which comprises or consists of the amino acid    sequence of SEQ ID NO: 13 (wherein the variable region is in bold    and the CDR sequences are in boxed italics)

[SEQ ID NO: 13] D I V L T Q S P D S L A V S L G E R A

A A P S V F I F P P S D E Q L K S G TA S V V C L L N N F Y P R E A K V Q WK V D N A L Q S G N S Q E S V T E Q DS K D S T Y S L S S T L T L S K A D YE K H K V Y A C E V T H Q G L S S P V T K S F N R G E C

For example, the antibody polypeptide may comprise or consist of twoheavy chains of SEQ ID NO: 12 and two light chains of SEQ ID NO: 13,joined together by disulphide bridges to form a typical IgG antibodystructure.

The antibody polypeptides of the invention may comprise or consist ofone or more amino acids which have been modified or derivatised.

Chemical derivatives of one or more amino acids may be achieved byreaction with a functional side group. Such derivatised moleculesinclude, for example, those molecules in which free amino groups havebeen derivatised to form amine hydrochlorides, p-toluene sulphonylgroups, carboxybenzoxy groups, t-butyloxycarbonyl groups, chloroacetylgroups or formyl groups. Free carboxyl groups may be derivatised to formsalts, methyl and ethyl esters or other types of esters and hydrazides.Free hydroxyl groups may be derivatised to form O-acyl or O-alkylderivatives. Also included as chemical derivatives are those peptideswhich contain naturally occurring amino acid derivatives of the twentystandard amino acids. For example: 4-hydroxyproline may be substitutedfor proline; 5-hydroxylysine may be substituted for lysine;3-methylhistidine may be substituted for histidine; homoserine may besubstituted for serine and ornithine for lysine. Derivatives alsoinclude peptides containing one or more additions or deletions as longas the requisite activity is maintained. Other included modificationsare amidation, amino terminal acylation (e.g. acetylation orthioglycolic acid amidation), terminal carboxylamidation (e.g. withammonia or methylamine), and the like terminal modifications.

It will be further appreciated by persons skilled in the art thatpeptidomimetic compounds may also be useful. The term ‘peptidomimetic’refers to a compound that mimics the conformation and desirable featuresof a particular peptide as a therapeutic agent.

For example, the said polypeptide includes not only molecules in whichamino acid residues are joined by peptide (—CO—NH—) linkages but alsomolecules in which the peptide bond is reversed. Such retro-inversopeptidomimetics may be made using methods known in the art, for examplesuch as those described in Meziere et al. (1997) J. Immunol. 159,3230-3237, which is incorporated herein by reference. This approachinvolves making pseudo-peptides containing changes involving thebackbone, and not the orientation of side chains. Retro-inversepeptides, which contain NH—CO bonds instead of CO—NH peptide bonds, aremuch more resistant to proteolysis. Alternatively, the said polypeptidemay be a peptidomimetic compound wherein one or more of the amino acidresidues are linked by a -y(CH₂NH)— bond in place of the conventionalamide linkage.

In a further alternative, the peptide bond may be dispensed withaltogether provided that an appropriate linker moiety which retains thespacing between the carbon atoms of the amino acid residues is used; itmay be advantageous for the linker moiety to have substantially the samecharge distribution and substantially the same planarity as a peptidebond.

It will be appreciated that the said polypeptide may conveniently beblocked at its N- or C-terminus so as to help reduce susceptibility toexo-proteolytic digestion.

A variety of un-coded or modified amino acids such as D-amino acids andN-methyl amino acids have also been used to modify mammalian peptides.In addition, a presumed bioactive conformation may be stabilised by acovalent modification, such as cyclisation or by incorporation of lactamor other types of bridges, for example see Veber et al., 1978, Proc.Natl. Acad. Sci. USA 75:2636 and Thursell et al., 1983, Biochem.Biophys. Res. Comm. 111:166, which are incorporated herein by reference.

It will be appreciated by persons skilled in the art that the antibodypolypeptides of the invention may be augmented with a functional moietyto facilitate their intended use, for example as an in vivo imagingagent or therapeutic agent.

Thus, in one embodiment, the antibody polypeptide is linked, directly orindirectly, to a therapeutic moiety.

Any suitable therapeutic moiety may be used. A suitable therapeuticmoiety is one that is capable of reducing or inhibiting the growth, orin particular killing, a prostatic cancer cell. For example, thetherapeutic agent may be a cytotoxic moiety. A cytotoxic moiety maycomprise or consist of one or more radioisotopes. For example, the oneor more radioisotopes may each be independently selected from the groupconsisting of beta-emitters, Auger-emitters, conversionelectron-emitters, alpha-emitters, and low photon energy-emitters. Itmay be desired that the one or more radioisotopes each independently hasan emission pattern of locally absorbed energy that creates a highabsorbed dose in the vicinity of the agent. Exemplary radioisotopes mayinclude long-range beta-emitters, such as ⁹⁰Y, ³²P, ¹⁸⁶Re/¹⁸⁸Re; ¹⁶⁶Ho,⁷⁶As/⁷⁷As, ⁸⁹Sr, ¹⁵³Sm; medium range beta-emitters, such as ¹³¹I, ¹⁷⁷Lu,⁶⁷Cu, ¹⁶¹Tb, ¹⁰⁵Rh; low-energy beta-emitters, such as ⁴⁵Ca or ³⁵S;conversion or Auger-emitters, such as ⁵¹Cr, ⁶⁷Ga, ⁹⁹Tc^(m), ¹¹¹In,^(114m)In, ¹²³I, ¹²⁵I ²⁰¹Tl, and alpha-emitters, such as ²¹²Bi, ²¹³Bi,²²³Ac, ²²⁵Ac, ²¹²Pb, ²⁵⁵Fm, ²²³Ra, ¹⁴⁹Tb and ²²¹At. Other radionuclidesare available and will be possible to use for therapy.

In another embodiment, it may be desired that the therapeutic moiety orcytotoxic moiety is not a moiety as disclosed as a “tracer” in WO2006/087374 A1, in particular at page 11, lines 7-15 thereof.

In one preferred embodiment, the antibody polypeptide is linked to (orotherwise labelled with) the radioisotope ¹⁷⁷Lu.

Alternatively, the therapeutic moiety may comprise or consist of one ormore therapeutic (such as cytotoxic) drugs, for example, a cytostaticdrug; an anti-androgen drug; cortisone and derivatives thereof; aphosphonate; a testosterone-5-α-reductase inhibitor; a boron addend; acytokine; thapsigargin and its metabolites; a toxin (such as saporin orcalicheamicin); a chemotherapeutic agent (such as an antimetabolite); orany other therapeutic or cytotoxic drug useful in the treatment ofprostatic carcinoma.

Exemplary therapeutic/cytotoxic drugs may, for example, include:

-   -   Cytostatics, in particular those with dose-limiting        side-effects, including but not limited to cyclophosamide,        chlorambucil, ifosfamide, busulphane, lomustine, taxanes,        estramustine phosphate and other nitrogen mustards, antibiotics        (including doxorubicine, calicheamicines and esperamicine),        vinca alkaloids, azaridines, platinum-containing compounds,        endostatin, alkyl sulfonates, nitrosoureas, triazenes, folic        acid analoges, pyrimidine analoges, purine analogs, enzymes,        substituted urea, methyl-hydrazine derivatives, daunorubicin,        amphipathic amines,    -   Anti-androgens such as flutamide and bikalutamide and        metabolites thereof;    -   Cortisone and derivatives thereof;    -   Phosphonates such as diphophonate and buphosphonate;    -   Testosterone-5-α-reductase inhibitors;    -   Boron addends;    -   Cytokines;    -   Thapsigargin and its metabolites;    -   Other agents used in the treatment of prostatic carcinoma.

Alternatively, the cytotoxic moiety may comprise or consist of one ormore moieties suitable for use in activation therapy, such as photonactivation therapy, neutron activation therapy, neutron induced Augerelectron therapy, synchrotron irradiation therapy or low energy X-rayphoton activation therapy.

For example, with the antibody polypeptides of the invention there willbe the potential of using synchrotron radiation (or low energy X-rays)for the advancement of radiotherapy, primarily focusing on so calledphoto-activation radiotherapy (PAT), in which the local energydeposition from external X-ray irradiation is enhanced in the cancertissue by the interaction with a pre-administered, high-Ztumor-targeting agent.

The PAT treatment modality utilises monochromatic X-rays from asynchrotron source, such as provided by the ID17 biomedical beamline atthe European Synchrotron Radiation Facility (ESRF) in Grenoble, and asanticipated to be available at other facilities in the future such asthe new Swedish synchrotron facility, Max-IV.

As a further potential treatment modality, research on “induced Augerelectron tumour therapy” is the coming European Spallation Source (ESS)in Lund, and hopefully a medical experimental station. Reactor-producedthermal and semi-thermal neutrons have for long been used forBoron-Neutron-Capture-Therapy, BNCT, both for pre-clinical experimentsand for treatment of brain tumours with the induced alpha-particles andthe recoil nucleus (⁷L) that give a high locally absorbed energy. Asimilar approach is to use neutrons and suitable tumour-targetingmolecules labelled with stable nuclei with high cross-section forneutrons. Antibodies or peptides can for instance be labelled withstable Gadolinium (¹⁵⁷Gd) and act as the target molecule for theneutrons that are captured by the Gd-nucleus, so called GadoliniumNeutron Capture Therapy (GdNCT). By Monte Carlo techniques, the dosedistribution in the tumour and the surrounding tissues is calculated asit results from γ-photons, neutrons, nuclear recoils, as well ascharacteristic x-rays, internal conversion and Auger-electrons fromgadolinium or other potential elements.

As discussed above, the therapeutic moiety (such as a radioisotope,cytotoxic moiety or the like) may be linked directly, or indirectly, tothe binding moiety (such as an antibody or fragment thereof). Suitablelinkers are known in the art and include, for example, prostheticgroups, non-phenolic linkers (derivatives of N-succimidyl-benzoates;dodecaborate), chelating moieties of both macrocyclics and acyclicchelators, such as derivatives of1,4,7,10-tetraazacyclododecane-1,4,7,10,tetraacetic acid (DOTA),deferoxamine (DFO), derivatives of diethylenetriaminepentaacetic avid(DTPA), derivatives ofS-2-(4-Isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triaceticacid (NOTA) and derivatives of1,4,8,11-tetraazacyclodocedan-1,4,8,11-tetraacetic acid (TETA),derivatives of 3,6,9,15-Tetraazabicyclo[9.3.1]-pentadeca-1(15),11,13-triene-4-(S)-(4-isothiocyanatobenzyl)-3,6,9-triacetic acid (PCTA),derivatives of5-S-(4-Aminobenzyl)-1-oxa-4,7,10-triazacyclododecane-4,7,10-tris(aceticacid) (DO3A) and other chelating moieties. The use of such linkers maybe particularly appropriate in circumstances wherein the agent comprisesor consists of an antibody or fragment thereof as the binding moietylinked, via a linker, to a radioisotope as the therapeutic moiety.

One preferred linker is DTPA, for example as used in¹⁷⁷Lu-DTPA-[antibody polypeptide of the invention].

A further preferred linker is deferoxamine, DFO, for example as used in⁸⁹Zr-DFO-[antibody polypeptide of the invention].

Optionally, the antibody polypeptide of the invention may (or may not)further comprises a detectable moiety. For example, a detectable moietymay comprise or consist of a radioisotope, such as a radioisotopeselected from the group consisting of ^(99m)Tc, ¹¹¹In, ⁶⁷Ga, ⁶⁸Ga, ⁷²As,⁸⁹Zr, ¹²³I and ²⁰¹Tl Optionally, the agent may comprise a pair ofdetectable and cytotoxic radionuclides, such as ⁸⁶Y/⁹⁰Y or ¹²⁴I/²¹¹At.Alternatively, the agent may comprise a radioisotope that is capable ofsimultaneously acting in a multi-modal manner as a detectable moiety andalso as a cytotoxic moiety to provide so-called “Multimodalitytheragnostics”. The binding moieties may thus be coupled tonanoparticles that have the capability of multi-imaging (for example,SPECT, PET, MRI, Optical, or Ultrasound) together with therapeuticcapability using cytotoxic drugs, such as radionuclides or chemotherapyagents. Also included with the present invention is the possibility oftreatment by hyperthermia using high frequency alternating magneticfields and accompanied ultrasound imaging.

Alternatively, the detectable moiety may comprise or consist of aparamagnetic isotope, such as a paramagnetic isotope is selected fromthe group consisting of ¹⁵⁷Gd, ⁵⁵Mn, ¹⁶²Dy, ⁵²Cr and ⁵⁶Fe.

In the case that the antibody polypeptide comprises a detectable moiety,then the detectable moiety may be detectable by an imaging techniquesuch as SPECT, PET, MRI, optical or ultrasound imaging.

Therapeutic and detectable moieties may be conjugated or otherwisecombined with the antibody polypeptide using methods well known in theart (for example, the existing immunoconjugate therapy, gemtuzumabozogamicin [tradename: Mylotarg®], comprises a monoclonal antibodylinked to the cytotoxin calicheamicin).

In a further embodiment, the antibody polypeptide of the invention isused to treat prostate cancer in the form of a formulation comprising apopulation of antibody polypeptide molecules. In one option, all (orsubstantially all, such as greater than 90%, 95%, 99%, 99.9% or more, byweight) of the antibody polypeptide molecules in the population comprisethe same therapeutic moiety. In another option, the population comprisesa mixture of other agents with different therapeutic moieties. Thisoption will give possibilities to enhance the effects of targetedradionuclide therapy using various agents such chemotherapy agents,hormonal therapy agents or other combination of therapies in which thetargeting agent not only delivers therapeutically active radionuclidesto tumor associated antigens but also simultaneously radiosensitizes thetargeted tumor cells by modulating (e.g. triggering or blocking) anintracellular signaling cascade. This option is also useful in treatingthe prostate cancer with a mixture of cytotoxic agents, for example,using a cocktail of alpha- and different ranges of beta-emitters, or acocktail of radionuclides with different range, LET (linear energytransfer) and RBE (relative biological effect), for combined treatmentof large tumors, micrometastases, and single tumor cells. In oneembodiment, long-range emitters may be used for treatment of largetumors, and short-range emitters may be used for the treatment ofsmaller tumours such as micrometastases, and single tumor cells.

Optionally, the antibody polypeptide of the present invention may (ormay not) further comprises a moiety for increasing the in vivo half-lifeof the agent. Exemplary moieties for increasing the in vivo half-life ofthe agent may include polyethylene glycol (PEG), human serum albumin,glycosylation groups, fatty acids and dextran. PEG may be particularlycontemplated.

It will be appreciated that the polypeptides of the invention may belyophilised for storage and reconstituted in a suitable carrier prior touse, e.g. through freeze drying, spray drying, spray cooling, or throughuse of particle formation (precipitation) from supercritical carbondioxide. Any suitable lyophilisation method (e.g. freeze-drying, spraydrying, cake drying) and/or reconstitution techniques can be employed.It will be appreciated by those skilled in the art that lyophilisationand reconstitution can lead to varying degrees of activity loss and thatuse levels may have to be adjusted upward to compensate. Preferably, thelyophilised (freeze dried) polypeptide loses no more than about 1% ofits activity (prior to lyophilisation) when rehydrated, or no more thanabout 5%, 10%, 20%, 25%, 30%, 35%, 40%, 45%, or no more than about 50%of its activity (prior to lyophilisation) when rehydrated.

Methods for the production of polypeptides of the invention are wellknown in the art.

Conveniently, the polypeptide is or comprises a recombinant polypeptide.Suitable methods for the production of such recombinant polypeptides arewell known in the art, such as expression in prokaryotic or eukaryotichosts cells (for example, see Sambrook & Russell, 2000, MolecularCloning, A Laboratory Manual, Third Edition, Cold Spring Harbor, N.Y.,the relevant disclosures in which document are hereby incorporated byreference).

Antibody polypeptides of the invention can also be produced using acommercially available in vitro translation system, such as rabbitreticulocyte lysate or wheatgerm lysate (available from Promega).Preferably, the translation system is rabbit reticulocyte lysate.Conveniently, the translation system may be coupled to a transcriptionsystem, such as the TNT transcription-translation system (Promega). Thissystem has the advantage of producing suitable mRNA transcript from anencoding DNA polynucleotide in the same reaction as the translation.

It will be appreciated by persons skilled in the art that polypeptidesof the invention may alternatively be synthesised artificially, forexample using well known liquid-phase or solid phase synthesistechniques (such as t-Boc or Fmoc solid-phase peptide synthesis).

A second aspect of the invention provides an isolated nucleic acidmolecule encoding an antibody polypeptide of the invention, or acomponent polypeptide chain thereof. By “nucleic acid molecule” weinclude DNA (e.g. genomic DNA or complementary DNA) and mRNA molecules,which may be single- or double-stranded.

In one embodiment, the nucleic acid molecule is a cDNA molecule.

It will be appreciated by persons skilled in the art that the nucleicacid molecule may be codon-optimised for expression of the antibodypolypeptide in a particular host cell, e.g. for expression in humancells (for example, see Angov, 2011, Biotechnol. J. 6(6):650-659).

In a preferred embodiment, the nucleic acid molecule of the inventioncomprises

-   (a) the nucleotide sequence of SEQ ID NO: 14

[SEQ ID NO: 14] CAG GTT CAG CTG CAG GAA AGC GGA CCT GGC TTGGTG AAA CCC AGC GAT ACC CTT AGC CTG ACA TGTGCT GTG TCT GGC AAT TCC ATC ACT TCC GAC TATGCG TGG AAC TGG ATT CGG CAA CCA CCG GGA AAAGGG CTC GAG TGG ATA GGG TAC ATC AGC TAT TCTGGT TCA ACC ACG TAC AAT CCC TCA CTG AAG AGTAGG GTT ACC ATG TCC AGA GAC ACC TCC AAG AACCAG TTC AGC CTG AAG CTG AGT AGT GTG ACA GCCGTA GAT ACA GCC GTC TAT TAC TGC GCA ACA GGGTAC TAC TAT GGC TCT GGC TTT TGG GGT CAA GGA ACT CTC GTC ACT GTG TCA AGC

and/or

-   (b) the nucleotide sequence of SEQ ID NO: 15

[SEQ ID NO: 15] GAC ATA GTG CTC ACT CAG AGC CCT GAT AGC TTGGCT GTC AGT CTT GGG GAA AGA GCC ACC ATC AACTGC AAA GCG TCC GAA AGC GTC GAG TAT TTC GGGACT AGC CTG ATG CAC TGG TAT CAG CAG AAA CCCGGA CAA CCG CCT AAG CTG CTG ATC TAT GCA GCCTCT AAT CGC GAA AGT GGC GTT CCA GAC AGG TTTTCC GGT TCT GGA TCA GGC ACA GAC TTC ACC CTCACG ATT TCC TCA CTG CAA GCT GAG GAT GTA GCCGTG TAC TAC TGT CAG CAG ACA CGG AAA GTG CCCTAC ACC TTT GGT CAG GGC ACA AAG CTG GAG ATT AAG

Also included within the scope of the invention are the following:

-   (a) a third aspect of the invention provides a vector (such as an    expression vector) comprising a nucleic acid molecule according to    the second aspect of the invention;-   (b) a fourth aspect of the invention provides a host cell (such as a    mammalian cell, e.g. human cell) comprising a nucleic acid molecule    according to the second aspect of the invention or a vector    according to the third aspect of the invention; and-   (c) a fifth aspect of the invention provides a method of making an    antibody polypeptide according to the first aspect of the invention    comprising culturing a population of host cells according to the    fourth aspect of the invention under conditions in which said    polypeptide is expressed, and isolating the polypeptide therefrom.

A sixth aspect of the invention provides a pharmaceutical compositioncomprising a pharmaceutically effective amount of an antibodypolypeptide of the first aspect of the invention and apharmaceutically-acceptable diluent, carrier or excipient.

Additional compounds may also be included in the pharmaceuticalcompositions, including, chelating agents such as EDTA, citrate, EGTA orglutathione.

The pharmaceutical compositions may be prepared in a manner known in theart that is sufficiently storage stable and suitable for administrationto humans and animals. For example, the pharmaceutical compositions maybe lyophilised, e.g., through freeze drying, spray drying, spraycooling, or through use of particle formation from supercriticalparticle formation.

By “pharmaceutically acceptable” we mean a non-toxic material that doesnot decrease the effectiveness of the kallikrein protein-bindingactivity of the agent of the invention. Such pharmaceutically acceptablebuffers, carriers or excipients are well-known in the art (seeRemington's Pharmaceutical Sciences, 18th edition, A. R Gennaro, Ed.,Mack Publishing Company (1990) and Handbook of PharmaceuticalExcipients, 3rd edition, A. Kibbe, Ed., Pharmaceutical Press (2000), thedisclosures of which are incorporated herein by reference).

The term “buffer” is intended to mean an aqueous solution containing anacid-base mixture with the purpose of stabilising pH. Examples ofbuffers are Trizma, Bicine, Tricine, MOPS, MOPSO, MOBS, Tris, Hepes,HEPBS, MES, phosphate, carbonate, acetate, citrate, glycolate, lactate,borate, ACES, ADA, tartrate, AMP, AMPD, AMPSO, BES, CABS, cacodylate,CHES, DIPSO, EPPS, ethanolamine, glycine, HEPPSO, imidazole,imidazolelactic acid, PIPES, SSC, SSPE, POPSO, TAPS, TABS, TAPSO andTES.

The term “diluent” is intended to mean an aqueous or non-aqueoussolution with the purpose of diluting the agent in the pharmaceuticalpreparation. The diluent may be one or more of saline, water,polyethylene glycol, propylene glycol, ethanol or oils (such assafflower oil, corn oil, peanut oil, cottonseed oil or sesame oil).

The term “adjuvant” is intended to mean any compound added to theformulation to increase the biological effect of the agent of theinvention. The adjuvant may be one or more of zinc, copper or silversalts with different anions, for example, but not limited to fluoride,chloride, bromide, iodide, thiocyanate, sulfite, hydroxide, phosphate,carbonate, lactate, glycolate, citrate, borate, tartrate, and acetatesof different acyl composition. The adjuvant may also be cationicpolymers such as cationic cellulose ethers, cationic cellulose esters,deacetylated hyaluronic acid, chitosan, cationic dendrimers, cationicsynthetic polymers such as poly(vinyl imidazole), and cationicpolypeptides such as polyhistidine, polylysine, polyarginine, andpeptides containing these amino acids.

The excipient may be one or more of carbohydrates, polymers, lipids andminerals. Examples of carbohydrates include lactose, glucose, sucrose,mannitol, and cyclodextrines, which are added to the composition, e.g.,for facilitating lyophilisation. Examples of polymers are starch,cellulose ethers, cellulose carboxymethylcellulose, hydroxypropylmethylcellulose, hydroxyethyl cellulose, ethylhydroxyethyl cellulose,alginates, carageenans, hyaluronic acid and derivatives thereof,polyacrylic acid, polysulphonate, polyethylenglycol/polyethylene oxide,polyethyleneoxide/polypropylene oxide copolymers,polyvinylalcohol/polyvinylacetate of different degree of hydrolysis, andpolyvinylpyrrolidone, all of different molecular weight, which are addedto the composition, e.g., for viscosity control, for achievingbioadhesion, or for protecting the lipid from chemical and proteolyticdegradation. Examples of lipids are fatty acids, phospholipids, mono-,di-, and triglycerides, ceramides, sphingolipids and glycolipids, all ofdifferent acyl chain length and saturation, egg lecithin, soy lecithin,hydrogenated egg and soy lecithin, which are added to the compositionfor reasons similar to those for polymers. Examples of minerals aretalc, magnesium oxide, zinc oxide and titanium oxide, which are added tothe composition to obtain benefits such as reduction of liquidaccumulation or advantageous pigment properties.

The antibody polypeptides of the invention may be formulated into anytype of pharmaceutical composition known in the art to be suitable forthe delivery thereof.

In one embodiment, the pharmaceutical compositions of the invention maybe in the form of a liposome, in which the antibody polypeptide iscombined, in addition to other pharmaceutically acceptable carriers,with amphipathic agents such as lipids, which exist in aggregated formsas micelles, insoluble monolayers and liquid crystals. Suitable lipidsfor liposomal formulation include, without limitation, monoglycerides,diglycerides, sulfatides, lysolecithin, phospholipids, saponin, bileacids, and the like. Suitable lipids also include the lipids abovemodified by poly(ethylene glycol) in the polar headgroup for prolongingbloodstream circulation time. Preparation of such liposomal formulationsis can be found in for example U.S. Pat. No. 4,235,871, the disclosuresof which are incorporated herein by reference.

The pharmaceutical compositions of the invention may also be in the formof biodegradable microspheres. Aliphatic polyesters, such as poly(lacticacid) (PLA), poly(glycolic acid) (PGA), copolymers of PLA and PGA (PLGA)or poly(caprolactone) (PCL), and polyanhydrides have been widely used asbiodegradable polymers in the production of microspheres. Preparationsof such microspheres can be found in U.S. Pat. No. 5,851,451 and in EP 0213 303, the disclosures of which are incorporated herein by reference.

In a further embodiment, the pharmaceutical compositions of theinvention are provided in the form of polymer gels, where polymers suchas starch, cellulose ethers, cellulose carboxymethylcellulose,hydroxypropylmethyl cellulose, hydroxyethyl cellulose, ethylhydroxyethylcellulose, alginates, carageenans, hyaluronic acid and derivativesthereof, polyacrylic acid, polyvinyl imidazole, polysulphonate,polyethylenglycol/polyethylene oxide, polyethyleneoxide/polypropyleneoxide copolymers, polyvinylalcohol/polyvinylacetate of different degreeof hydrolysis, and polyvinylpyrrolidone are used for thickening of thesolution containing the agent. The polymers may also comprise gelatin orcollagen.

Alternatively, the antibody polypeptides may simply be dissolved insaline, water, polyethylene glycol, propylene glycol, ethanol or oils(such as safflower oil, corn oil, peanut oil, cottonseed oil or sesameoil), tragacanth gum, and/or various buffers.

It will be appreciated that the pharmaceutical compositions of theinvention may include ions and a defined pH for potentiation of actionof the active antibody polypeptide. Additionally, the compositions maybe subjected to conventional pharmaceutical operations such assterilisation and/or may contain conventional adjuvants such aspreservatives, stabilisers, wetting agents, emulsifiers, buffers,fillers, etc.

The pharmaceutical compositions according to the invention may beadministered via any suitable route known to those skilled in the art.Thus, possible routes of administration include parenteral (intravenous,subcutaneous, and intramuscular), topical, ocular, nasal, pulmonar,buccal, oral, parenteral, and rectal. Also administration from implantsis possible. Infusion may be a desired route because of the potentiallyhigh cytotoxicity of the administered agent.

In one embodiment, the pharmaceutical compositions are administeredparenterally, for example, intravenously, intracerebroventricularly,intraarticularly, intra-arterially, intraperitoneally, intrathecally,intraventricularly, intrasternally, intracranially, intramuscularly orsubcutaneously, or they may be administered by infusion techniques. Theyare conveniently used in the form of a sterile aqueous solution whichmay contain other substances, for example, enough salts or glucose tomake the solution isotonic with blood. The aqueous solutions should besuitably buffered (for example, to a pH of from 3 to 9), if necessary.The preparation of suitable parenteral formulations under sterileconditions is readily accomplished by standard pharmaceutical techniqueswell known to those skilled in the art.

Formulations suitable for parenteral administration include aqueous andnon-aqueous sterile injection solutions which may contain anti-oxidants,buffers, bacteriostats and solutes which render the formulation isotonicwith the blood of the intended recipient; and aqueous and non-aqueoussterile suspensions which may include suspending agents and thickeningagents. The formulations may be presented in unit-dose or multi-dosecontainers, for example sealed ampoules and vials, and may be stored ina freeze-dried (lyophilised) condition requiring only the addition ofthe sterile liquid carrier, for example water for injections,immediately prior to use. Extemporaneous injection solutions andsuspensions may be prepared from sterile powders, granules and tabletsof the kind previously described.

Thus, the pharmaceutical compositions of the invention are particularlysuitable for parenteral, e.g., intravenous administration or localadministration to a tumour in a patient (for example, intra-tumourallyor peri-tumourally).

The pharmaceutical compositions will be administered to a patient in apharmaceutically effective dose, i.e. a therapeutically effectiveabsorbed dose of the therapeutic radionuclide.

In the context of therapeutic use of the antibody polypeptides of theinvention, a ‘pharmaceutically effective amount’, or ‘effective amount’,or ‘therapeutically effective’, as used herein, refers to that amountwhich provides a therapeutic effect for a given condition andadministration regimen. This is a predetermined quantity of activematerial calculated to produce a desired therapeutic effect inassociation with the required additive and diluent, i.e., a carrier oradministration vehicle. Further, it is intended to mean an amountsufficient to reduce and/or prevent, a clinically significant deficit inthe activity, function and response of the host. Alternatively, atherapeutically effective amount is sufficient to cause an improvementin a clinically significant condition in a host. As is appreciated bythose skilled in the art, the amount of a compound may vary depending onits specific activity. Suitable dosage amounts may contain apredetermined quantity of active composition calculated to produce thedesired therapeutic effect in association with the required diluent. Inthe methods and use for manufacture of compositions of the invention, atherapeutically effective amount of the active component is provided. Atherapeutically effective amount can be determined by the ordinaryskilled medical worker based on patient characteristics, such as age,weight, sex, condition, complications, other diseases, etc., as is wellknown in the art (see Example 8 below). The administration of thepharmaceutically effective dose can be carried out both by singleadministration in the form of an individual dose unit or else severalsmaller dose units and also by multiple administrations of subdivideddoses at specific intervals. Alternatively, the does may be provided asa continuous infusion over a prolonged period.

In the context of diagnostic use of the antibody polypeptides of theinvention, a ‘pharmaceutically effective amount’, or ‘effective amount’,or ‘diagnostically effective’, as used herein, refers to that amountwhich provides a detectable signal for in vivo imaging purposes.

The antibody polypeptides of the invention can be formulated at variousconcentrations, depending on the efficacy/toxicity of the compound beingused. The formulation may comprises the polypeptide at a concentrationof between 0.1 μM and 1 mM, between 1 μM and 500 μM, between 500 μM and1 mM, between 300 μM and 700 μM, between 1 μM and 100 μM, between 100 μMand 200 μM, between 200 μM and 300 μM, between 300 μM and 400 μM,between 400 μM and 500 μM and about 500 μM.

Typically, the therapeutic dose of the antibody polypeptide (with orwithout a therapeutic moiety) in a human patient will be in the range of100 μg to 700 mg per administration (based on a body weight of 70 kg).For example, the maximum therapeutic dose may be in the range of 0.1 to10 mg/kg per administration, e.g. between 0.1 and 5 mg/kg or between 1and 5 mg/kg or between 0.1 and 2 mg/kg. It will be appreciated that sucha dose may be administered at different intervals, as determined by theoncologist/physician; for example, a dose may be administered daily,twice-weekly, weekly, bi-weekly or monthly.

It will be appreciated by persons skilled in the art that thepharmaceutical compositions of the invention may be administered aloneor in combination with other therapeutic agents used in the treatment ofa prostate cancer, or before, after or at the same time as the treatmentof the patient with other therapeutic modalities for the treatment ofprostate cancer, such as other therapeutic antibodies, surgery (e.g.,radical prostatectomy), radionuclide therapy, brachytherapy, externalbeam radiation therapy, high-intensity focused ultrasound (HIFU),chemotherapy, oral chemotherapeutic drugs, cryosurgery (freezing thetumour), hormonal therapy (such as antiandrogen therapy), castration orcombinations of the foregoing.

A seventh aspect of the invention provides a kit comprising an antibodypolypeptide according to the first aspect of the invention or apharmaceutical composition according to the sixth aspect of theinvention, together with instructions for use of the same as describedherein.

An eighth aspect of the invention provides an antibody polypeptideaccording to the first aspect of the invention for use in medicine.

A ninth aspect of the invention provides an antibody polypeptideaccording to the first aspect of the invention for use in the treatmentand/or diagnosis of prostate cancer.

A tenth aspect of the invention provides a method of treatment ofprostate cancer in a subject, the method comprising administering to thesubject a therapeutically effective amount of a antibody polypeptideaccording to the first aspect of the invention.

By ‘treatment’ we include both therapeutic and prophylactic treatment ofthe patient. The term ‘prophylactic’ is used to encompass the use of anagent, or formulation thereof, as described herein which either preventsor reduces the likelihood of prostate cancer, or the spread,dissemination, or metastasis of localised prostate cancer in a patientor subject. The term ‘prophylactic’ also encompasses the use of anagent, or formulation thereof, as described herein to prevent recurrenceof prostate cancer in a patient who has previously been treated forprostate cancer.

An eleventh aspect of the invention provides a method of diagnosis ofprostate cancer in a subject, the method comprising administering to thesubject a diagnostically effective amount of a antibody polypeptideaccording to the first aspect of the invention.

By “diagnosis” we include the detection of prostate cancer cells, eitherin vivo (i.e. within the body of a patient) or ex vivo (i.e. within atissue or cell sample removed from the body of a patient).

The prostate cancer to be treated or diagnosed may be localised to theprostate, or may be a non-localised (that is, disseminated) prostatecancer. Prostate cancer localised to the prostate may, for example, beclassified as clinical T1 or T2 cancers according to the TNM system(abbreviated from Tumor/Nodes/Metastases) whereasnon-localised/disseminated prostate cancer may, for example, beclassified as clinical T3 or T4 cancers.

The prostate cancer to be treated or diagnosed may be a metastaticprostate cancer. Metastasis refers to the spread of a cancer from itsoriginal location to other sites in the body. For example, themetastatic prostate cancer to be treated or diagnosed may be ametastases present in the lymphatic system; in bone (including spine,vertebrae, pelvis, ribs); metastasis within pelvis, rectum, bladder, orurethra. Metastases present at other less common locations can also betreated with the present invention. The metastases may bemicrometastases. Micrometastase is a form of metastases in which thenewly formed tumors are generally too small to be detected, or detectedwith difficulty. For example, the present invention provides the skilledperson with means to treat single cancer cells or cell clusters, even ifthe presence of such cells or clusters are not possible to diagnose butexist, for example as occult disseminated disease.

Accordingly, it is anticipated that a particularly important technicaladvantage of the treatment provided by the present invention compared tothe prior art treatments of prostate cancer is the enhanced efficacy intreatment of disseminated and/or metastatic (including micrometastatic)prostate cancer.

Thus, in one embodiment, the invention provides antibody polypeptidesand methods for preventing or treatment metastasis of a primary prostatetumour.

Prostate cancer tends to develop in men over the age of fifty, morecommonly in men over 60, 65 or 70, and although it is one of the mostprevalent types of cancer in men, many never have symptoms, undergo notherapy, and eventually die of other causes. This is because cancer ofthe prostate is, in most cases, slow-growing, symptom-free, and sincemen with the condition are older they often die of causes unrelated tothe prostate cancer, such as heart/circulatory disease, pneumonia, otherunconnected cancers, or old age. About two-thirds of prostate cancercases are slow growing, the other third more aggressive and fastdeveloping.

Accordingly, the development of effective methods for the treatment anddiagnosis of prostate cancer is particularly important for management ofmore aggressive and fast developing forms of the cancer, particularly inyounger patient. Accordingly, in one embodiment, the invention relatesto the treatment or diagnosis of prostate cancer in a patient who isless than 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40 or less years oldat the time of diagnosis of prostate cancer and/or at the time oftreatment.

Men who have a first-degree relative (father or brother) with prostatecancer are thought to have twice the risk of developing prostate cancer,and those with two first-degree relatives affected are thought to have afive-fold greater risk compared with men with no family history.Accordingly, the invention may relate to the treatment or diagnose ofprostate cancer in a patient that is characterised in that one, two, ormore, family members, in particular first-degree family members (such asa father or brother), has been previously been diagnosed with prostatecancer.

The invention also relates to the treatment or diagnosis of prostatecancer in a patient, wherein the prostate cancer to be treated hascastration-resistant prostate cancer (CRPC). CRPC may be characterisedby typically becoming refractory to hormone treatment after one to threeyears, and resuming growth despite hormone therapy.

In the medical uses and methods of the invention, the antibodypolypeptide is typically injected or infused into the body of thepatient. In vivo, the antibody polypeptide then binds to tissues thatproduce the target antigen, hK2; primarily, prostate cancer cells andmetastases thereof. Upon binding, the antibody polypeptide may directlyexert a therapeutic effect (e.g. inducing cell death via ADCC, CDC or byvirtue of carrying a radioisotope or other cytotoxic moiety).Alternatively, the bound antibody polypeptide may serve as a diagnostic(imaging) tool, which may guide the choice of therapy or aid surgicalremoval of the cancer cells.

It will be appreciated by persons skilled in the art that the antibodypolypeptides of the invention may be used in combination with othertherapeutic and/or diagnostic agents/treatment, such as externalradiotherapy, surgery, cytostatic and androgen treatments.

The foregoing description focuses on embodiments of the presentinvention applicable to methods for the treatment and diagnosis ofprostatic cancer. However, it will be appreciated that the invention isnot limited to such applications but may be useful for post-operativeexaminations, and examinations during or after radiation, cytostatic,and androgen treatments.

In another embodiment RadioGuided Surgery (RGS) or Image-Guided Surgery(IGS) may be used to identify tracer-labeled antibody polypeptides ofthe invention during and/or before surgery. Thus, an antibodypolypeptide comprising a detectable moiety as discussed above may beadministered during and/or before surgery. In this embodiment theantibody polypeptides may first be infused. Thereafter, RGS/IGS may beused to identify hK2-producing tissue with a detection instrumentsensitive to the detectable moiety, during or before surgery. Thedetectable moiety may, for example, be a radiation emitting ormagnetic-sensitive detectable moiety; it may, for example, be an emitterof Cerenkov radiation and/or Bremsstrahlung; it may be a fluorescentlabel and/or a magnetic or magnetizable label. Accordingly, the RGS/IGSaccording to the present invention may, for example, be a method that isbased on the detection of optical, Cerenkov, Bremsstrahlung, or betaradiation; the detection of a radionuclide label, and/or may involvemagnetometry. RGS is well known to the person skilled in the art as asurgical technique that enables the surgeon to identify tissue “marked”by the detectable moiety.

The visualisations obtained according to the above methods may becombined with other radiological visualisation methods, such asSPECT/PET, computed tomography (CT), ultrasound (US), and magneticresonance imaging (MRI).

Accordingly, in a further aspect, the present invention also providesantibody polypeptides for use in medicine by administration to a patientwith prostate cancer before or during the surgery, such as RadioGuidedor Image-Guided Surgery.

A still further aspect of the invention provides an in vitro method forthe detection of prostate tumour cells in the blood of a subject, themethod comprising:

-   -   (a) providing a sample of blood from a subject to be tested;    -   (b) optionally, extracting and/or purifying cells present in the        blood sample;    -   (c) contacting an antibody polypeptide according to the first        aspect of the invention with cells present in the blood sample;    -   (d) determining (directly or indirectly) whether the antibody        polypeptide binds to free (i.e. uncomplexed) hK2        wherein the binding of the antibody polypeptide to free hK2 is        indicative of the presence of prostate tumour cells in the blood        of a subject.

Thus, the method comprises performing an assay to determine whether theblood sample contains free hK2; the presence of free hK2 beingindicative of the presence of prostate tumour cells in the blood of asubject.

Persons skilled in the art will appreciate that there are many ways toperform such an assay. For example, the immunoassay could be eitherhomogeneous or, more preferably, heterogenous. The assay could alsoperformed in either a competitive or, more preferably, a non-competitiveformat.

In the case of the heterogeneous, non-competitive assay, an exemplaryprotocol could be:

-   -   (a) providing a sample of blood from a subject to be tested;    -   (b) optionally, extracting and/or purifying cells present in the        blood sample;    -   (c) contacting a solid phase immobilized antibody polypeptide        according to the first aspect of the invention with cells        present in the blood sample;    -   (d) washing to remove soluble components (not bound to solid        surface);    -   (e) adding the tracer, i.e. another anti-hK2 specific antibody        labelled with a reporter molecule/particle;    -   (f) washing to remove unbound tracer antibody; and    -   (g) detecting the signal from the tracer antibody

Between steps b & c or c & d, there should typically be an incubationperiod to allow the cell to produce soluble hK2, then for it to bedetected.

An additional aspect of the invention provides an in vitro method forthe detection of prostate tumour cells in the tissue of a subject, themethod comprising

-   -   (a) providing a sample of tissue (such an a histological sample)        from a subject to be tested;    -   (b) optionally, extracting and/or purifying cells present in the        tissue sample;    -   (c) contacting an antibody polypeptide according to the first        aspect of the invention with cells present in the tissue sample;    -   (d) determining (directly or indirectly) whether the antibody        polypeptide binds to free (i.e. uncomplexed) hK2        wherein the binding of the antibody polypeptide to free hK2 is        indicative of the presence of prostate tumour cells in the        tissue of a subject.

In one embodiment of the above in vitro methods, step (d) is performedby ELISA. However, any assay suitable for detecting antibody-antigeninteractions in vitro may be used.

In an additional embodiment, the method further comprises quantificationof the prostate tumour cells in the sample.

In a further embodiment of the above in vitro methods, the method is forthe diagnosis of prostate cancer in a subject.

The use of the word “a” or “an” when used in conjunction with the term“comprising” in the claims and/or the specification may mean “one,” butit is also consistent with the meaning of “one or more,” “at least one,”and “one or more than one.”

These, and other, embodiments of the invention will be betterappreciated and understood when considered in conjunction with the abovedescription and the accompanying drawings. It should be understood,however, that the above description, while indicating variousembodiments of the invention and numerous specific details thereof, isgiven by way of illustration and not of limitation. Many substitutions,modifications, additions and/or rearrangements may be made within thescope of the invention without departing from the spirit thereof, andthe invention includes all such substitutions, modifications, additionsand/or rearrangements.

The following drawings form part of the present specification and areincluded to further demonstrate certain aspects of the presentinvention. The invention may be better understood by reference to one ormore of these drawings in combination with the detailed description ofspecific embodiments presented herein.

FIG. 1: The sequences of the heavy and light chain variable regions ofthe exemplary humanised 11B6 Fab fragment of the invention.

FIG. 2: SDS-PAGE gel with native and reduced samples of murine andhumanised 11B6 antibodies.

FIG. 3: Association phases upon binding of the test 11B6 antibodies tohK2 on a chip.

FIG. 4: Dissociation phases of the test 11B6 antibodies.

FIG. 5: Biodistribution of ¹⁷⁷Lu-labelled humanised 11B6 antibodies.

FIG. 6: Exemplary SPECT image showing binding of ¹⁷⁷Lu-labelled h11B6 toprostate tumour in mice.

FIG. 7: Percentage uptake of ¹⁷⁷Lu-labelled h11B6 and m11B6 in tumourand bone.

FIG. 8: Ratio of percentage uptake per gram of ¹⁷⁷Lu-labelled h11B6 andm11B6 in tumour to bone.

FIG. 9: Kinetics of the (a) humanised 11B6 antibody and (b) murine 11B6antibody.

FIG. 10: Clearance of ¹⁷⁷Lu-labelled h11B6 and m11B6 from the blood.

FIG. 11: Representative photographs of tumour size before (top image)and after (bottom image) treatment with ¹⁷⁷Lu-11B6.

FIG. 12: Summary of the effect of (a) single radioactivity amount ‘D’ of¹⁷⁷Lu-11B6, (b) double radioactivity amount ‘2×D’ of ¹⁷⁷Lu-11B6 and (c)control treatment on tumour size in LNCaP xenografts.

FIG. 13: (a) tumour growth data and (b) a SPECT image for one LNCaPxenografts mouse treated with a single dose ¹⁷⁷Lu-11B6.

FIG. 14: Tumour volume as a function of days post injection for (a)animals receiving ¹⁷⁷Lu-labelled h11B6 antibody according to theinvention, (b) animals receiving ¹⁷⁷Lu-labelled non-specific IgG‘isotype control’ antibody and (c) animals receiving NaCl only.Treatment was administered on Day 0. Animals were terminated in theevent of the following occurrences: large tumour volumes (diameter >14mm); large weight loss (weight loss >15% compared to initial weight);negatively affected general condition; or a combination of all thesethree parameters. (numbers to the right are the ID number of eachanimal)

FIG. 15: Kaplan-Meier curve for the three treatment groups shown in FIG.14. Solid line: ¹⁷⁷Lu-h11B6; broken line: ¹⁷⁷Lu-labelled non-specificIgG Isotype control′ antibody; dotted line: NaCl.

The following examples are included to demonstrate particularembodiments of the invention. It should be appreciated by those of skillin the art that the techniques disclosed in the examples which followrepresent techniques discovered by the inventor to function well in thepractice of the invention, and thus can be considered to constitutespecific modes for its practice. However, those of skill in the artshould, in light of the present disclosure, appreciate that many changescan be made in the specific embodiments which are disclosed and stillobtain a like or similar result without departing from the spirit andscope of the invention.

EXAMPLES Example 1—Cloning of 11B6 from Hybridoma Cell Line

Reagents

Monoclonal antibody 11B6 producing hybridoma cell line was used for mRNAextraction and production of antibodies which were further affinitypurified for protein sequencing (Väisänen et al., 2004).

Restriction enzymes, FastAP and T4 DNA ligase were from Fermentas,primers from the University of Turku, Department of Biotechnology(WO252) and from Thermo Scientific. DNA purifications were done withQiagen's Gel extraction and PCR purification kits.

mRNA Extraction and cDNA Synthesis

mRNA was extracted from 11B6 MAb producing hybridoma cells (5E6 cells)with QuickPrep Micro mRNA purification kit (Amersham Biosciences) andcDNA synthesis from the mRNA was done with Applied Biosystems'High-capacity cDNA archive kit according to instructions.

Amplification of Antibody Genes from cDNA

N-terminal sequences of the purified 11B6 MAb heavy (H) and light (L)chains were determined by Edman degradation at the University ofHelsinki protein sequencing service. Light chain sequence was DIVLTQSPAS[SEQ ID NO: 16] and the heavy chain sequence DVQLQESGPG [SEQ ID NO: 17].IMGT database comparison of amino acids identified the genes: IGKV3 andIGHV3, respectively. The complementary regions for forward PCR primers(degenerate) were designed based on the DNA sequences (found by NCBIBLAST) coding the N-terminal amino acids. Reverse primer used to clonethe heavy chain was designed to bind C_(H1). In the case of the lightchain, two reverse primers were used; the one used in the first PCRbinds to C_(L) and the other one used in second PCR to the border ofV_(L) and C_(L). All primers also contain the restriction enzymerecognition sites needed for cloning (later underlined).

Light chain forward primer was SfiI_DIVLTQSPAS [SEQ ID NO: 16]:

(5′-TTACTCGCGGCCCAGCCGGCCATGGCGGAYATHGTRYTVACNCARTCTCC-3′; [SEQ ID NO: 18])and reverse primers WO252

(5′-GCGCCGTCTAGAATTAACACTCATTCCTGTTGAA-3′, XbaI; [SEQ ID NO: 19]) andCpoI_JK2 (5′-GATACAGTTGGTGCAGCATCGGTCCGTTTTATTTCCAGCTTGGTCCCCCCT-3′; [SEQ ID NO: 20]).

Heavy chain forward primer was NotI_DVQLQESGPG [SEQ ID NO: 17]

(5′-TGCTGCTGGCGGCCGCTCCAGCCATGGCTGAYGTVCARCTKCAGGAGTCDGG-3′; [SEQ ID NO: 21])and reverse primer asCH1_SacI

(5′-CGCCACCAGAGCTCTCACAATCCCTGGGCACAATTTTC-3′; [SEQ ID NO: 22]).

V_(L)+C_(L) fragment was amplified in PCR reaction containing 100 ngcDNA as template, 0.2 mM dNTP's, 0.5 μM primers SfiI DIVLTQSPAS [SEQ IDNO: 16] and WO252, 1× Phusion HF buffer and 0.6 U Phusion DNA polymerase(Finnzymes). Amplification was done by protocol of 98° C. 30 sec, 30cycles of 98° C. 7 sec, 50° C. 20 sec, 72° C. 20 sec, and finalextension of 72° C. 10 min. After sequencing the PCR product and findingout the sequence of V_(L)-C_(L) border the PCR for actual cloning wasdone again from cDNA in a reaction like above except with primersSfiI_DIVLTQSPAS [SEQ ID NO: 16] and CpoI_JK2 to clone only the V_(L)part. Amplification was done by protocol of 98° C. 30 sec, 10 cycles of98° C. 7 sec, 60° C. 20 sec, 72° C. 20 sec, 25 cycles of 98° C. 7 sec,56° C. 20 sec, 72° C. 20 sec, and final extension of 72° C. 10 min.

V_(H)+C_(H1) fragment was amplified in a reaction like with V_(L) exceptwith primers NotI_DVQLQESGPG [SEQ ID NO: 17] and asCH1_SacI.Amplification protocol was 98° C. 30 sec, 30 cycles of 98° C. 7 sec, 64°C. 20 sec, 72° C. 20 sec, and final extension of 72° C. 10 min.

Cloning

The correct sized products were purified from the preparative agarosegel. V_(L) was digested with SfiI and CpoI, V_(H)+C_(H1) with SacI andNotI. Recipient vector pAK400 5404 FAb Ich (modified from pAK400,Krebber et al., 1997) was digested separately with both enzymecombinations, fragments dephosphorylated with FastAP and purified fromthe preparative gel.

Digested 1186 V_(L) and the corresponding vector fragment were ligatedwith T4 DNA ligase and transformed by electroporation into Escherichiacoli XL1-Blue cells (Stratagene) to produce vector pAK400-11B6-VL.Ligation product of SacI+NotI digested V_(H)+C_(H1) and vector fragmentwas called pAK400-11B6-VH+CH1. Correct clones were confirmed by DNAsequencing and comparing sequences to the original protein sequences andto the antibodies found on the database (BLAST search).

To construct the complete 11B6 Fab, both previously made constructs weredigested with NotI and SacI. Vector pAK400-11B6-VL was used as recipientvector to which V_(H)+C_(H1) from vector pAK400-11B6-VH+CH1 wasinserted. Ligation and transformation were done as above. Theconstructed pAK400 11B6 FAb Ich vector was confirmed with restrictionenzyme analysis.

REFERENCES

-   Barbas C F 3rd, Kang A S, Lerner R A, Benkovic S J. (1991) Assembly    of combinatorial antibody libraries on phage surfaces: The gene Ill    site. Proc. Nat. Acad. Sci., Vol. 88, pp. 7978-7982-   Biomagnetic Techniques in Molecular Biology: Technical handbook.    Dynal A. S, 2^(nd) edition, 1995-   Krebber A, Bornhauser S, Burmester J, Honegger A, Willuda J,    Bosshard H R, Plückthun A. (1997) Reliable cloning of functional    antibody variable domains from hybridomas and spleen cell    repertoires employing a reengineered phage display system. J Immunol    Methods. 201(1):35-55-   Lilja H, Christensson A, Dahlén U, Matikainen M T, Nilsson O,    Pettersson K, Lövgren T. (1991) Prostate-specific antigen in serum    occurs predominantly in complex with alpha 1-antichymotrypsin. Clin    Chem. 37(9):1618-25-   Pajunen M, Saviranta P, Jauria P, Karp M, Pettersson K, Mäntsälä P,    Lovgren T. (1997) Cloning, sequencing, expression and    characterization of three anti-estradio1-17beta Fab fragments.    Biochim Biophys Acta. 1351(1-2):192-202-   Väisänen V, Eriksson S, Ivaska K K, Lilja H, Nurmi M,    Pettersson K. (2004) Development of sensitive immunoassays for free    and total human glandular kallikrein 2. Clin Chem. 50(9):1607-17

Example 2—Humanisation of the 11B6 Antibody

The variable domain of the murine anti-hK2 antibody 11B6 was humanisedusing CDR-grafting method. In this approach, the complementaritydetermining regions (CDR) of the murine antibody were grafted to thevariable heavy and light domain frameworks. In addition residues at CDRregions, the residues in the certain critical positions at the frameworkregions were retained as murine-like rather than turned to human-like inorder to maintain the conformation of grafted CDR loops as similar aspossible to their conformation in the parental murine antibodies.

Kabat numbering scheme (Kabat et al., 1991) is used throughout thisdescription.

Homology Modelling

An homology model of the murine 11B6 antibody was generated by usingautomatic Web antibody modelling—Server (VAM;http://antibody.bath.ac.uk/index.html). The model was used for visualinspection based evaluation of the importance of the residues differingin between the parental murine antibodies and the human immunoglobulinsequences used as frameworks for the variable domain humanization,respectively.

Design of the 11B6 Humanised V-Domain Sequences

V_(L) Domain Design

The amino acid sequence of the murine 11B6 light chain variable domainwas compared to the database of human immunoglobulin germline sequencesin NCBI using ClustalW sequence alignment program. 11B6 V_(L) was foundshare the highest similarity with the human germline gene B3(IGKV4-1*01), the only member of the human V_(K4) family. Concerning theJ-segment encoding the C-terminal part of the variable domain sequence,the human J_(κ2) was found to be the most similar with the correspondingregion of the murine 11B6.

The human B3 gene together with sequence of IGKJ2 were used as aframework for the grafting of the CDR-loops (FIG. 1) from the lightchain of parental murine antibody 11B6. Residue of murine origin(leucine) was introduced in the position 4 of V_(L) instead ofhuman-like methionine. This Vernier zone (Foote and Winter, 1992)residue is located directly underneath CDR1 and CDR3 loops of lightchain. At the position 54 in CDR-L2 human-like arginine was used insteadof murine-like valine. According to modelling, the residue at thisposition is unlikely form direct interaction with the antigen, however,Arg54 seems to form a salt bridge with the negatively charged aspartateat the position 60 in the human framework. It was considered unlikelythat the residue at the position 24 in CDR-L1 is involved in antigencontacting. Consequently, human-like lysine was introduced in thisposition instead of murine-like arginine.

V_(H) Domain Design

The amino acid sequence of the murine 11B6 heavy chain variable domainwas compared to the database of human immunoglobulin germline sequencesin NCBI using clustalW sequence alignment program. 11B6 V_(H) was foundhave the highest similarity with the human V_(H4) family member VH4-28.Concerning J-segment encoding the C-terminal part of the variable domainsequence, the human J_(H1) was found to be the most similar with thecorresponding region of the murine 11B6.

The human V_(H4)-28 gene together with sequence of J_(H1) were used as aframework for the grafting of the CDR-loops (FIG. 1) from the heavychain of the parental murine antibody 11B6.

Murine-like residues asparagine and threonine were introduced at thepositions 27 and 30 of V_(H), respectively. Although not belonging toCDR-H1 according to the Kabat definition (Kabat et al., 1991; FIG. 1),they are classified as CDR residues by some other CDR definitionprocedures such as that by Chothia (1989). Residues 27 and 30 can affectthe structure of the other parts of the CDR-H1 and possibly participatein direct contacts with the antigen. The residue at the position 71 isknown the play important role in maintaining the conformation of theCDR-H2 (Tramontano et al., 1990), and murine-like arginine was used hereinstead of human-like valine. At the position 94 preceding the importantCDR-H3 loop, the murine 11B6 derived residue threonine was introducedinstead of human VH4-28 like arginine. In addition, it was consideredunlikely that the residue at the position 60 in CDR-H2 is involved inantigen contacting. Therefore, human-like asparagine was introduced atthis position instead of murine-like serine.

The genes encoding the humanized 11B6 as Fab fragment, where thedesigned V_(H) and V_(L) domains were joined to the human C_(H1) andhuman C_(κ) constant domains, respectively, were purchased as asynthetic construct (Genscript, US). The genes were cloned into theexpression vector pAK400Fab modified from pAK400 (Krebber et al., 1997)using SfiI restriction enzyme having recognition sites on the eitherside of the Fab cassette. The vector was transformed into E. coli XL-1blue cells for the expression of the humanised Fab fragment.

The sequences of the heavy and light chain variable regions of theexemplary humanised 11B6 Fab fragment of the invention are shown in FIG.1.

REFERENCES

-   Chothia, C., Lesk, A. M., Tramontano, A., Levitt, M., Smith-Gill, S.    J., Air, G., Sheriff, S., Padlan, E. A., Davies, D., Tulip, W. R.,    Colman, P. M., Spinelli, S., Alzari, P. M., and Poljak, R. J. (1989)    Conformations of immunoglobulin hypervariable regions Nature, 342,    877-883-   Kabat, E. A., Wu, T. T., Perry, H. M., Gottesman, K. S and    Foeller, C. (1991) Sequences of Immunological Interest, 5^(th)    edit., NIH, Bethesda, Md.-   Krebber A, Bornhauser S, Burmester J, Honegger A, Willuda J,    Bosshard H R, Plückthun A. (1997) Reliable cloning of functional    antibody variable domains from hybridomas and spleen cell    repertoires employing a reengineered phage display system. J Immunol    Methods. 201(1):35-55-   Tramontano, A., Chothia, C. and Lesk, A. M. (1990) Framework Residue    71 is a Major Determinant of the Position and Conformation of the    Second Hypervariable Region in the V_(H) Domains of    Immunoglobulins. J. Mol. Biol. 215, 175-182

Example 3—Expression and Purification of h11B6

HEK293 cells were expanded in to a 2 L suspension culture in FreeStyle293 Expression Medium (Life Technologies). The cell density was on theday for transfection 1×10⁶ cells/ml.

The nucleotide sequences encoding the component heavy or light chains(i.e. SEQ ID NOs: 14 and 15, respectively) were codon-optimized forexpression in mammalian cells, synthesized and cloned to IgG expressionvectors. The plasmid DNA (expression vector) containing the nucleotidesequences for the heavy and light chains was then mixed with thetransfection agent and incubated for 10 min in RT. The DNA-transfectionagent-mix was slowly added to cell culture while slowly swirling theflask. The transfected cell culture was then incubated at 37° C., 8% CO₂on an orbital shaker platform rotating at approx. 135 rpm, for sevendays.

Culture medium was harvest by centrifugation and filtered through 5 μm,0.6 μm and 0.22 μm filter systems.

Antibodies were purified by Protein G chromatography and the buffer waschanged to PBS pH 7.4 by dialysis; subsequently, the antibodies wereconcentrated by ultrafiltration.

Concentration was measured by absorbance.

DNA: Light chain: p11B6VLhV1 hk (4300 bp) amount: 0.35 mg

-   -   Heavy chain: p11B6VHhV1 hIgG1 (4900 bp) amount: 0.6 mg

The DNA amounts were not optimized.

Transfection agent: proprietary (however, suitablecommercially-available transfection agents are readily available, suchas Xfect™ Transfection Reagent (Clontech), Lipofectamine (LifeTechnologies), FuGENE® HD Transfection Reagent (Promega), FreeStyle™ MaxReagent (Invitrogen), DEAE-dextran, polyethylenimine and calciumphosphate).

Overall yield: 13.1 mg (˜6.5 mg/L)

Example 4—Characterisation of h11B6: Affinity

Aims of Study

The aim of the study was to investigate the binding kinetics betweenfour variants of the antibody 11B6 and the antigen hK2 by using thetechnique of Surface Plasmon Resonance (SPR) on a Biacore instrument.

In order to investigate the quality of the protein samples (antibodiesand antigen), a SDS-PAGE gel was run prior to the SPR experiments.

In a Pre-Study, different parameters were investigated in order to findthe appropriate conditions for the experiments in the Study.

In the Study, multiple binding measurements were performed for the fourantibodies and the antigen. From the collected data, the association anddissociation rate constants (k_(on) and k_(off)) and the dissociationconstants (KD) were calculated and reported here.

Reagents and Instrument Information

Following solutions of the four antibodies and one antigen were providedby Diaprost AB:

-   -   m11B6 stock: a-ehk211B6 14.12013 PP, 3.41 mg/ml: 0.9% NaCl, 100        μl    -   h11B6 stock: Innovagen Lot 90476.30 2013 Apr. 12, 1 mg/ml: PBS        pH 7.4, 320 μl    -   h11B6-DTPA stock: 0.2M Na-acetate pH 5.5, 0.9 mg/ml, 340 μl    -   h11B6-DFO stock: 5 mg/ml gentisin acid in 0.2M ammonium acetate        pH 5.5, 1.6 mg/ml, 400 μl    -   hK2 stock: 26.6 μg/ml frakt 2 fr 7 SL+protein inh 5/2-02 1% BSA

All the samples were aliquoted and kept in −20° C. freezer prior toanalysis.

All binding experiments were performed on CM4 chip on a Biacore 3000instrument. The chip and all the reagents needed for activation,immobilization, deactivation, binding and regeneration were purchasedfrom GE Healthcare and used according to the guidelines from themanufacturer.

SDS-Page

(a) Description of the Experiment

The reagents provided by Diaprost AB were run on a TRIS-Tricine 10-20%acrylamide gel from Novex according to the guidelines from themanufacturer.

Two series of the protein samples, native and reduced, were runsimultaneously on the same gel together with a standard sample.

Each sample in the native series contained: 1-1.3 μg of the protein,TRIS-buffer pH 8.8, SDS and loading buffer.

Each sample in the reduced series contained: 1-1.3 μg of the protein,TRIS-buffer pH 8.8, SDS, loading buffer and 0.04% v/vbeta2-merkaptoethanol (the reducing agent).

The staining of the gel was performed in commasie brilliant bluesolution of acetic acid, ethanol and water with the correspondingproportions of 0.7, 3.0, 6.3.

The destaining of the gel was performed in the solution of acetic acid,ethanol and water with the corresponding proportions of 0.7, 3.0, 6.3.

(b) Results & Conclusions

The results are shown in FIG. 2.

It is evident from these results that the antibody and antigen samplesare of high quality and purity.

Affinity Study

(a) Immobilisation of Antigen on a CM4 Chip

Activation of the chip CM4-2 was performed according to manufacturer'sguidelines for amine coupling using EDC and NHS mixture.

A solution containing 2.96 μg/ml of the antigen hK2 (stock solution ofhK2 diluted in 10 mM NaAc-buffet pH 3.8) was flown over channels fc2-4on the chip CM4-2 in order to immobilize the antigen to the chip. Flowrate: 5 μl/min, volume: 200 μl.

Target RU ≤ Mw/10 Mw(hk2) = 25 900 Da Target RU (hk2) ≤ 2590

Channel fc1 was used as a blank.

The following immobilization was achieved:

fc2 = 1104 RU fc3 = 731 RU fc4 = 688 RU

All channels (fc1-4) were blocked by ethanolamine after activation andimmobilization.

These data demonstrate that appropriate immobilization was achievedusing 2.96 μg/ml of the antigen.

(b) Investigation of the Association Phase

The association phase of the four antibodies to the chip CM4-2 wasfollowed for 4-5 minutes when solutions of 5 different concentrations ofeach antibody (stock solutions diluted in HSP-buffer) were flown overthe channels fc2-4 on the chip CM4-2 with a rate of 30 μl/min.

The investigated concentrations for each antibody were: 100, 50, 25,12.5 and 6.25 nM.

Additionally association data was obtained from the experiments wherethe dissociation process was followed for 480 minutes.

In total, 18 individual association experiments for each antibody wereperformed.

The signal from the blank, fc1, was subtracted for all the data.

In FIG. 3, the association phases in channel fc2 on chip CM-2 for eachof the antibodies at the 5 different concentrations are shown.

We found that after 4-5 minutes, we were able to fit the data for theassociation processes.

(c) Investigation of the Dissociation Phase

The dissociation phase was followed for 480 minutes for each of theantibodies after flowing a solution of 50 nM of the antibody for 5minutes over the channels fc2-4 on the chip CM4-2 with a rate of 30μl/min (FIG. 4).

The signal from the blank, fc1, is subtracted in all the data used inthe calculations of the dissociation rate constant.

The data indicate that the dissociation processes are very slow. For allfour antibodies, the signal in channel fc4 was drifting and thedissociation process could not be followed in that channel.

(d) Estimation of the Dissociation Rate Constant (k_(off))

The dissociation phase data was fitted and the dissociation rateconstants (koff) were estimated (see Table 2).

TABLE 2 Std Antibody K_(off)(10⁻⁵s⁻¹)fc2 K_(off)(10⁻⁵s⁻¹)fc3K_(off)(10⁻⁵s⁻¹)fc4 Mean dev m11B6 1.9 4.9 — 3.4 ±2.1 h11B6 6.4 6.9 —6.7 ±0.4 h11B6- 6.3 19.1 — 12.7 ±9.1 DTPA h11B6- 5.8 5.5 — 5.7 ±0.2 DFO

Based on the two measurements taken for each antibody, there appears tobe no significant difference between the dissociation rate constants(k_(off)) of the tested antibodies.

(e) Estimation of the Association Rate Constant (k_(on))

In order to estimate the association rate constants, the dissociationrate constants (Table 2) were used in the fitted equations.

All fitted data was used in order to calculate an average value of theassociation rate constant and the standard deviation for each antibody(see Table 3).

TABLE 3 Antibody No. of expts fitted Mean k_(on) (10⁵M⁻¹s⁻¹) Std devm11B6 18/18 2.48 ±0.85 h11B6 15/18 1.17 ±0.38 h11B6-DTPA 17/18 1.82±0.54 h11B6-DFO 18/18 1.11 ±0.22

Based on the 15-18 measurements taken for each antibody, there appearsto be no significant difference between the association rate constants(k_(on)) of the tested antibodies.

(f) Estimation of the Dissociation Constant (k_(D))

Dissociation constant (K_(D)) for each of the tested antibodies areshown in Table 4.

TABLE 4 Antibody Mean K_(D) 10⁻¹¹ M Std dev m11B6 19 ±15 h11B6 65 ±25h11B6-DTPA 93 ±78 h11B6-DFO 54 ±13

The dissociation constants (K_(D)) are in the 10⁻¹² M range for all fourantibodies.

Although not statistically significant, the dissociation constant forthe humanised antibody appears to be higher than that of the parentmurine antibody.

Conjugation of the humanised antibody does not appear to affect theaffinity noticeably since the K_(D) is not significantly changed forh11B6-DTPA or h11B6-DFO.

Summary

-   -   The association processes are very fast for all four antibodies        and the association rate constants (k_(on)) are all in the 10⁵        M⁻¹ s⁻¹ range based on 15-18 experiments for each antibody.    -   The dissociation processes are very slow and almost in the range        of technical limitations of Biacore. The dissociation rate        constants (k_(off)) are all in the 10⁻⁵ s⁻¹ range based on two        experiments for each antibody.    -   The dissociation constants (K_(D)) are in the 10⁻¹² M range for        all four antibodies.

Example 5—Characterisation of h11B6: Aggregation

Executive Summary

Dynamic light scattering (DLS) studies have been carried out on 4variants of the IgG in order to study their propensity to aggregate. TheDLS results show that all constructs have a reasonable size (200 kDa orslightly above 200 kDa assuming a spherical protein) and little or noaggregation.

Objective

To characterise four IgG constructs with respect to oligomeric stateusing dynamic light scattering. Insulin was used as a control.

Results

Dynamic Light Scattering

Phosphate buffered saline (PBS pH 7.4) was filtrated through 0.22 micronfilter. The delivered protein was diluted to 0.1 mg/ml in PBS pH 7.4.Dynamic light scattering was measured at 20° C. in duplicate samplesusing the Malvern APS equipment. Each sample was measured three times.The dilution buffer was used as control to make sure that the buffer wasreasonably free from dust and aggregates, FIG. 1c . All samples could bereliably measured using the number distribution function. The averageradius of the most abundant species was calculated along with thepolydispersity of the species. The average mass distribution of thisspecies was also calculated, see table 5.

TABLE 5 Dynamic light scattering data derived from size distributionAverage Polydispersity Mass distribution Construct radius (nm) (%) (%)Insulin 2.8 28 100 h11B6 5.7 15 99.2 M11B6 5.7 17 100 DFO-h11B6 6.0 2299.9 H11B6-DTPA 6.1 22 100 Polydispersity = Standard deviation ofradius/Average radius × 100%

The insulin control (4 mg/ml 20 mM Na2HPO4, 10 mM Na3EDTA) have anaverage radius of 2.8 nm which is about 37 kDa. In solution insulin isknown to form hexamers of about 35 kDa. A radius of 5.7 nm correspondsto a molecular weight of about 200 kDa for a protein having a perfectspherical shape. A radius of 6.1 nm corresponds to a molecular weight ofabout 230 kDa for a protein having a perfect spherical shape. This isreasonably close to the molecular weight of 150 kDa for IgG molecules,which means that most of the samples primarily consist of monomericand/or dimeric IgG molecules. The reason for not excluding dimers isthat light scattering give a rough size estimate based on molecularshape and this makes it difficult to separate monomers and dimers buteasy to separate large aggregates from monomers or monomers fromhexamers (as in the insulin case).

Conclusions

Dynamic light scattering shows that all constructs have a reasonablesize and little or no aggregation. The size distributions for all fourconstructs are overlapping (data not shown).

Example 6—Characterisation of h11B6: In Vivo Biodistribution

This study compares biodistribution in vivo of murine 11B6 and human11B6 when labeled to ¹⁷⁷Lu.

Material and Methods

Materials

¹⁷⁷Lu was purchased from Mallinkrodt Medical BV, Petten, Holland.

All chemicals were obtained from Sigma Aldrich and buffers were preparedin-house using analytical grade water (unless otherwise noted).

The parent murine antibody m11B6, with specific for the human kallikrein2, was obtained from the University of Turku, Finland.

m11B6 heavy chain [SEQ ID NO: 23]:DVQLQESGPGLVKPSQSLSLTCTVTGNSITSDYAWNWIRQFPGNRLEWMGYISYSGSTTYSPSLKSRFSITRDTSKNQFFLQLNSVTPEDTATYFCATGYYYGSGFWGQGTLVTVSSAKTTPPSVYPLAPGSAAQTNSMVTLGCLVKGYFPEPVTVTWNSGSLSSGVHTFPAVLESDLYTLSSSVTVPSSPRPSETVTCNVAHPASSTKVDKKIVPRDCGCKPCICTVPEVSSVFIFPPKPKDVLTITLTPKVTCVVVDISKDDPEVQFSWFVDDVEVHTAQTQPREEQFNSTFRSVSELPIMHQDWLNGKEFKCRVNSAAFPAPIEKTISKTKGRPKAPQVYTIPPPKEQMAKDKVSLTCMITDFFPEDITVEWQWNGQPAENYKNTQPIMNTNGSYFVYSKLNVQKSNWEAGNTFTCSVLH EGLHNHHTEKSLSHSPGKm11B6 light chain [SEQ ID NO: 24]:DIVLTQSPASLAVSLGQRATISCRASESVEYFGTSLMHWYRQKPGQPPKLLIYAASNVESGVPARFSGSGSGTDFSLNIQPVEEDDFSMYFCQQTRKVPYTFGGGTKLEIKRTDAAPTVSIFPPSSEQLTSGGASVVCFLNNFYPKDINVKWKIDGSERQNGVLNSWTDQDSKDSTYSMSSTLTLTKDEYERHNSYTCEATHKTSTSPIVKSFNRNEC

A humanised counterpart antibody, h11B6, was produced as described inExamples 2 and 3 above (see FIG. 1).

For in vivo studies, the prostate carcinoma cell lines LNCaP expressinghK2 (ATCC, Manassas, Va., USA) and DU145 (ATCC, Manassas, Va., USA) wereused. Cells were cultured in RPMI 1640 medium supplemented with 10%fetal bovine serum and PEST (penicillin 100 IU/ml and 100 μg/mlstreptomycin). The cells were maintained at 37° C. in a humidifiedincubator with 5% CO₂ and were detached with trypsin-EDTA solution(0.25% trypsin, 0.02% EDTA in buffer, Thermo Scientific). Matrigelmatrix from BD-biosciences (San-Jose, Calif., USA) was used whenxenografting LNCaP cells. NMRI-Nu, (Charles River) and Balb/c-Nu (inhouse bread) mice were inoculated with the two cell lines.

Conjugation and Radiolabelling

Conjugation of CHX-A″-DTPA with 11B6:

Solutions of the murine and humanised 11B6 mAbs in PBS was adjusted topH 9.2 using 0.07 M sodium borate buffer, prior to being concentrated onan Amicon Ultra-2 centrifugal filter (2 ml, 100 K). The resultantprotein solution was then conjugated with chelator CHX-A″-DTPA(Macrocyclics, USA) in a molar ratio of 3:1 chelator to antibody at 40°C. The reaction was terminated after 4 h and CHX-A″-DTPA-11B6(DTPA-11B6) was separated from free chelate by size-exclusionchromatography on a NAP-5 column (GE Healthcare), equilibrated with 20ml 0.2 M ammonium acetate buffer, pH 5.5. The conjugated 11B6 antibodieswere eluted with 1 ml ammonium acetate buffer.

Radiolabeling of DTPA-11B6:

Murine and humanised DTPA-11B6, in ammonium acetate buffer pH 5.5 wasmixed with a predetermined amount of ¹⁷⁷LuCl₃. A final activity of0.5-0.6 MBq per subject was used for biodistribution or a final activityof 18-20MBq per subject was used for SPECT studies. After incubation atroom temperature for 2 h, the labeling was terminated and purified on aNAP-5 column, equilibrated with PBS

Animal Studies

All animal experiments were performed in accordance with nationallegislation on laboratory animals' protection.

Male immunodeficient nude mice, NMRI-Nu, (6-8 wk old) and Balb/c-Nu,were used for this study. All mice were xenografted with LNCaP cells orDU145 on their left or right flank, 8-10 million cells, in 100 μl growthmedium and 100 μl Matrigel.

Biodistribution Studies

Biodistribution studies were performed on both h11B6 and m11B6.

Six groups (n=4) of mice were injected intravenously with either 20 μgof h11B6 or 20 μg m11B6 labeled with ¹⁷⁷Lu. The animals were sacrificedat 24 h p.i., 48 h p.i and 72 h p.i. and organs of interest wereanalysed with an automated NaI(Tl) well-counter with a 3-inch NaI (Tl)detector (1480 WIZARD, Wallac Oy, Turku, Finland).

The tissue uptake value, expressed as percent injected dose per gramtissue (% IA/g), was calculated as:% IA/g=(tissue radioactivity/injected radioactivity)/organ weight×100wherein for iv injections:Injected radioactivity=Average radioactivity in controlsyringes−radioactivity in used syringe−radioactivity in tail

The organs were also weighed following dissection.

Kinetic Data

DThe time-% ID curve is represented as a straight line ID(t)=k*t+m up to48. Based on the data from the second and third time-points (48respectively 72 h), a mono-exponential curve (ID(t)=ID(0)e^(−λt)) isapplied for the time interval [48,∞[. If, however, lambda becomes anegative value, i.e. that the ID is increasing between 48 and 72 h, thetime ID curve in this time-interval is instead modeled as a straightline, and the pharmaceutical is assumed to be retained in the organ from72 hours and onwards. To obtain the time-activity curves, the physicalhalf-life is applied.

Note—in some figures, ID is termed “IA”; these expressions are usedinterchageably herein.

Results

Biodistribution of Humanised ¹⁷⁷Lu-11B6

The biodistribution of ¹⁷⁷Lu-h11B6 is shown in FIG. 5.

The antibody rapidly accumulates in the LNCaP tumour within by 24 hours,and the radioactivity remains high at 72 hours.

Initially, high levels of h11B6 are also evident in the blood andkidneys, which reduce over the following 48 hour period as the antibodyis cleared from the body. Such biokinetics are an inevitable andexpected consequence of intravenous injection of any radiolabelledantibody.

All other organs, such as bone and muscle, show low levels ofradioactivity.

These data demonstrate that ¹⁷⁷Lu-h11B6 can effectively target prostatecancer cells in vivo.

FIG. 6 shows an exemplary SPECT image, in which binding of ¹⁷⁷Lu-h11B6to LNCaP tumour cells within a xenografted mouse is clearly evident.

¹⁷Lu-h11B6 Exhibits an Unexpectedly Better Therapeutic Ratio

Comparison of the biodistribution data for humanised ¹⁷⁷Lu-11B6 withthat for the parent murine antibody (¹⁷⁷Lu-m11B6) revealed an unexpectedand advantageous difference.

As shown in FIG. 7, uptake of ¹⁷⁷Lu-h11B6 into the LNCaP tumour iselevated by about 20% at 72 post injection compared to ¹⁷⁷Lu-m11B6.Concomitantly, uptake of ¹⁷⁷Lu-h11B6 into healthy bone is reduced byabout 40% at 72 post injection compared to ¹⁷⁷Lu-m11B6.

FIG. 8 shows the data expressed as a ratio of antibody uptake in tumourversus healthy bone, at 24, 48 and 72 hours post injection. By 72 hours,this ratio is markedly increased for the humanised 11B6 antibody.

Dosimetry Calculations

Calculation of absorbed doses provides a more sophisticated measure ofdifferences in the kinetics of the humanised antibodies of the inventionrelative to those of the parent murine 11B6 antibody.

The absorbed dose was calculated according to the MI RD-schemaD(r_(T)←r_(S))=Ã(r_(S))·S(r_(T)←r_(S)), where Ã is the total number ofdisintegrations in an source organ, and S is the absorbed dose per unitof disintegrations (see Bolch et al., 2009, J. Nucl. Med. 50:477-484,the disclosures of which are incorporated herein by reference). The Ãwas calculated as the time-integral over the time-activity curve. TheS-factor was based on mice-specific Monte Carlo simulations using theMoby-phantom (see Larsson et al., 2011, Acta Oncol. 50:973-980 andKeenan et al., 2010, J. Nucl. Med. 50:471-476). To get the totalabsorbed dose, all organs were considered as being source—as well astarget sources.

Calculated absorbed dose values for different tissues are shown in Table6.

TABLE 6 Absorbed dose (Gy/MBq) Organ m11B6 h11B6 Blood 0.915101 1.16768Heart 1.11217 0.756549 Lung 0.445617 0.677907 Liver 0.2652 0.447948Spleen 0.396808 0.612251 Intestines 0.189362 0.426528 Kidney 0.2919660.913515 Bone 0.193169 0.179905 Brain 0.0332977 0.0556325 Testes0.178707 0.516442 Tumour 1.21858 2.20389 Bone 0.309455 0.385407 (marrow)

As can been seen from Table 6, tumour absorbed dose increases from 1.21Gy/MBq for m11B6 to 2.2 Gy/MBq for h11B6, i.e. an increase with 80%. Theratios of tumour to bone marrow absorbed doses increases from 3.9 form11B6 to 5.6 for h11B6 about 40%. Herein, the enhanced therapeuticefficacy for h11B6 compared to m11B6 is shown and indicates that higherabsorbed doses to the tumor can be given with less normal organtoxicity.

Antibody Clearance from the Blood

Analysis of blood levels for the humanised and murine 11B6 antibodies isshown in FIG. 10.

The results suggest that h11B6 may be cleared from the blood slightlyquicker than the murine 11B6 antibody. If so, such an enhanced clearancerate for the humanised antibody may also of therapeutic benefit from asafety perspective, potentially allowing higher activities to beadministered.

An enhanced clearance rate may also be beneficial for external imaging

Conclusions

The results of this study demonstrate the following:

-   -   the humanised 11B6 antibody, ¹⁷⁷Lu-h11B6, effectively targets        prostate tumours in vivo;    -   the humanised 11B6 antibody exhibits an unexpectedly better        therapeutic ratio than its parent murine antibody (as determined        by the ratio of uptake in tumours to uptake in healthy bone);        and    -   the humanised 11B6 antibody may be cleared from the blood        slightly quicker than the murine 11B6 antibody.

Taken together, these findings provide compelling evidence of theenhanced therapeutic efficacy of humanised 11B6 antibodies in thetreatment (and diagnosis) of prostate cancer.

Since the humanised and murine antibodies are targeted to the sameantigen (namely, human kallikrein 2), the calculated difference in theupdate ratio in tumour to healthy bone marrow cannot readily bepredicted or explained (particularly given that the humanised antibodyappears to exhibit a lower affinity for the target hK2 antigen comparedto the parent murine antibody; see Example 4).

The difference in the relative uptake in tumour compared to healthy bonebetween the humanised and murine 11B6 antibodies is of considerableimportance since this comparison provides a measure of the therapeuticratio. A higher value for this ratio (as evident for the humanised 11B6antibody) is indicative of a better therapeutic antibody. In particular,a higher therapeutic ratio means that higher absorbed doses oftherapeutically-radiolabelled h11B6 can be administered to achieve abetter therapeutic effect (since binding of the humanised antibody tohealthy tissue and organs is much lower than for the murine antibody).The higher ratio also indicates that h11B6 will be better than themurine antibody for diagnostic purposes (since it equates to a lowersignal to noise ratio, allowing imaging of smaller tumours includingmetastases).

In conclusion, the data demonstrate that humanisation of the 11B6antibody gives an enhanced possibility for early diagnosis and anunexpectedly higher therapeutic efficacy in the treatment prostatecancer.

Example 7—Demonstration of Diagnostic and Therapeutic Efficacy

The aim of this study was to confirm the utility of 11B6, a mAb thatspecifically targets an epitope inside the catalytic cleft of hK2, as avehicle to deliver highly toxic radionuclides specifically to the sitesof prostate cancer growth. In this proof of concept study, we labelledthe parent murine 11B6 antibody with 177Lu, a low energy beta particlethat also employs gamma emission, enabling SPECT-imaging to beperformed.

Materials & Methods

Materials

¹⁷⁷Lu was purchased from Mallinkrodt Medical BV, Petten, Holland. TheCyclone™ Storage Phosphor System and the OptiQuant™ image analysissoftware (Perkin Elmer, Wellesley, Mass., USA) was used to measure theradioactivity on the ITLC (instant thin layer chromatography) strips(Biodex, US) for determining labeling kinetics and radiochemical purity.All chemicals were obtained from Sigma Aldrich and the buffers werein-house prepared using analytical grade water if not otherwise noted.The mAb 11B6 is an antibody specific for the human kallikrein 2 with anaffinity for this antigen of about 1.2 nM; see FIG. 1 (obtained from theUniversity of Turku, Finland). For the in vivo studies, the prostatecarcinoma cell lines LNCaP expressing hK2 (ATCC, Manassas, Va., USA)were used. Cells were cultured in RPM′ 1640 medium supplemented with 10%fetal bovine serum and PEST (penicillin 100 IU/ml and 100 μg/mlstreptomycin). The cells were maintained at 37° C. in a humidifiedincubator with 5% CO₂ and were detached with trypsin-EDTA solution(0.25% trypsin, 0.02% EDTA in buffer, Thermo Scientific).

Conjugation and Radiolabeling

Conjugation of CHX-A″-DTPA with 11B6:

A solution of the mAb 11B6 in PBS was adjusted to pH 9.2 using 0.07 Msodium borate buffer. The sample was concentrated on an Amicon Ultra-2centrifugal filter (2 ml, 100 K). The protein solution was conjugatedwith the chelator CHX-A″-DTPA (Macrocyclics, USA) in a molar ratio of3:1 chelator to antibody at 40° C. The reaction was terminated after 4 hand CHX-A″-DTPA-11B6, from now on called DTPA-11B6, was separated fromfree chelate by size-exclusion chromatography on a NAP-5 column (GEHealthcare) equilibrated with 20 ml 0.2 M ammonium acetate buffer, pH5.5. Conjugated 11B6 and 5A10 was eluted with 1 ml ammonium acetatebuffer.

Radiolabeling of DTPA-11B6:

DTPA-11B6 in ammonium acetate buffer pH 5.5 was mixed with apredetermined amount of ¹⁷⁷LuCl₃. After incubation at room temperaturefor 2 h, the labeling was terminated and purified on a NAP-5 column,equilibrated with PBS. Labeling efficiency and labeling kinetics weremonitored with ITLC strips, eluted with 0.2 M citric acid. In thissystem, the radiolabelled conjugate remains at the origin line, whilefree Lu-177 migrates with the front of the solvent. The radioactivitydistribution was determined with a PhosphorImager system (Perkin Elmer,Wellesley, Mass., USA) using the Optiquant as quantification software(Perkin Elmer, Wellesley, Mass., USA).

Animal Studies

All animal experiments were performed in accordance with nationallegislation on laboratory animals' protection. The animal study has beenapproved by the local Ethics Committee for Animal Research. Maleimmunodeficient nude mice, NMRI, (6-8 wk old) purchased from TaconicEurope (Bomholt, Denmark) were used for this study.

Xenografts of hK2-expressing LNCaP prostate carcinoma cells weresubcutaneously implanted in the right flank and/or left flank at about10*10⁶ cells per injection.

Animals that developed LNCaP tumors were divided into groups andinjected with either the therapeutic agent 177Lu-DTP-11B6 or with acontrol, see Table 7 below:

TABLE 7 Animals Group nr Treatment 5 animals/group 1 NaCl (control) 11groups 2 Unspecific Ab labeled with 177Lu—low Total = 55 absorbed doseanimals 3 Unspecific ab labeled with 177Lu—high absorbed dose 4 Only177Lu—low absorbed dose 5 Only 177Lu—high absorbed dose 6177Lu-DTPA-m11B6: A/4 7 177Lu-DTPA-m11B6: A/2 8 177Lu-DTPA-m11B6: A 9177Lu-DTPA-m11B6: 2*A 10 177Lu-DTPA-m11B6: 3*A 11 Only m11B6 A = 26.7MBq

All animals included were continuously measured and weighed within aninterval of 3-4 days.

Initially some animals got a lower activity (8MBq) of ¹⁷⁷Lu-DTPA-11B6for investigation of the localization of the therapeutic agent usingSPECT. One mouse from group 8 was also studied with SPECT. These animalshad their organs removed and an automated NaI(T1) well-counter with a3-inch NaI (Tl) detector (1480 WIZARD, Wallac Oy, Turku, Finland) wasused to quantify radioactivity in these tissue samples.

To study the effect on the bone marrow blood samples (10 μL) were takenregularly. Blood samples were collected twice a week for 8 weekspost-injection and WBC counts, RBC counts, and platelet counts wereanalyzed in a Medonic Cell Analyzer-Vet CA530 Vet (Boule Medical,Stockholm, Sweden). At the time of blood sampling, the weight andphysical condition of the animals were monitored. Toxicity was evaluatedby monitoring animals for loss of body weight, decline in generalcondition, and hematologic toxicity.

Tumor volume was measured with a caliper. The length l, with w andthickness t were measured and the volume was calculated.

Therapy Planning

Based on the relationship between absorbed dose and biological effect onthe bone marrow in rats undergoing Radioimmunotherapy with 90Y and 177Lu(see Larsson et al., 2012, Med. Phys. 39(7):4434-43), it could beestimated that the LD50 for bone marrow would be in the order of 12 Gy.In the literature LD50 for acute irradiation of rats and mice are thesame, about 9 Gy (for example, see Radiobiology for the radiologist,Hall & Giacca (Eds), 2006, 6^(th) edition).

The therapies were then designed from the assumption of a tolerableabsorbed dose of 12 Gy to bone marrow. Then, from the dosimetrycalculations the activity corresponding to this absorbed dose wascalculated.

Corresponding doses/activities were used for the controls.

Results

Animal Tumor Shrinkage

FIG. 11 shows how the tumor in one of the mice (visible on the animal'sflank, under the skin) decreases in volume following treatment.

Radioimmunotherapy Results

FIG. 12 shows the results for the study groups with administeredactivities (a) D, (b) 2×D and (c) a control group (where D=26.7 MBq).

There is a clear trend of decrease of tumor volume in both treatmentgroups. The onset of tumor shrinkage is seen already a few days afterinjection of 177Lu-m11B6. In the control group there is an increase oftumor volume after the injection of NaI solution.

FIG. 13(a) shows the results for one of the mice in the group injectedwith activity A. Here, the tumor grows steadily from day one until daysix when activity A of 177Lu-m11B6 is administered. Following treatment,a rapid drop in tumor volume is observed.

In the SPECT study (8 d pi) the tumor volume is shown with stillactivity present; see FIG. 13(b).

Conclusion

The present study with exemplary antibody 177Lu-m11B6 clearlydemonstrates the therapeutic efficacy of hK2-targeted antibodies againstprostate cancer tumours in vivo.

Example 8—Therapeutic Efficacy of an Exemplary ¹⁷⁷Lu-Labeled Humanised11B6 Antibody of the Invention in Prostate Cancer Xenografts

Materials & Methods

Antibodies, Conjugation and Radiolabeling

Antibodies:

The exemplary humanised monoclonal antibody 11B6 (IgG1/kappa, transientexpressed in HEK 293 cells), comprising a heavy chain according to SEQID NO:12 and a light chain according to SEQ ID NO:13, was provided byInnovagen AB, Lund (1 mg/ml in PBS pH 7.4, Lot No. 90476.30). Anon-specific IgG antibody was utilised as an isotype control (IgGantibody from mouse serum, Sigma 1-8765).

Conjugation:

The exemplary h11B6 non-specific IgG control antibody were conjugatedwith the chelator CHX-A″-DTPA (Macrocyclics, USA) as followed: Asolution of the antibody was concentrated on an Amicon Ultra-2centrifugal filter (2 mL, 100 K) and was later adjusted to pH 9.2 using0.07 M sodium borate buffer (Sigma Aldrich).

Coupling of the chelator compound CHX-A″-DTPA to the protein solution ina molar ratio of approximately 3:1 (chelator to antibody) was performedsimilarly to a previously described method (see Almqvist et al). Thecoupling efficiency, i.e. number of obtained chelators per antibody canbe determined by a spectrophotometric method (Pippin et al) but was notanalysed in this study. However, the coupling preferably should notexceed 3 chelators/antibody in order to avoid damage to the protein. Thechelator was added to the protein and the solution was incubated withgentle shaking at 40° C.

The reaction was terminated after 4 h and CHX-A″-DTPA-h11B6, referred toas DTPA-h11B6, was separated from free chelate by size-exclusionchromatography on a NAP-5 column (GE Healthcare) equilibrated with 20 ml0.2 M ammonium acetate buffer (Sigma Aldrich), pH 5.5. Conjugated h11B6was eluted with 1 ml ammonium acetate buffer and aliquoted samples werestored at −20° C.

Conjugation of the IgG control antibody was controlled in the similarway as above.

Radiolabeling:

Conjugated h11B6 or IgG control antibody (typically 200-300 μL of ˜1μg/μL in 0.2 M sodium acetate buffer pH 5.5) was mixed with apredetermined amount (˜200-300 MBq) of ¹⁷⁷LuCl₃ (IDB Holland) andincubated at room temperature for 1.5-2 h. After incubation, thelabeling was terminated and purified on a NAP-5 column (GE Healthcare),equilibrated with PBS (Thermo Scientific). Labeling efficiency wasmonitored with instant thin layer chromatography (Biodex, USA), elutedwith 0.2 M citric acid (Sigma Aldrich). In this system, the radiolabeledconjugate remains at the origin line, while free ¹⁷⁷Lu migrates with thefront of the solvent. The radioactive distribution was determined with aCyclone Storage Phosphor System using the Optiquant as quantificationsoftware (both from Perkin Elmer).

The radiolabeling of the IgG control antibody was performed in thesimilar way as above.

Therapy Study

Cell Lines: LNCaP (hK2+) were purchased from American Type CultureCollection (ATCC). Cells were cultured in RPMI 1640 medium (ThermoScientific) supplemented with 10% fetal bovine serum (Thermo Scientific)with penicillin 100 IU/mL and 100 μg/mL streptomycin (ThermoScientific). The cells were maintained at 37° C. in a humidifiedincubator at 5% CO₂ and were detached with trypsin-EDTA solution (ThermoScientific).

All animal experiments were conducted in compliance with the nationallegislation on laboratory animals' protection, and with the approval ofthe Ethics Committee for Animal Research (Lund University, Sweden).In-house bred male immunodeficient Balb/c nude mice (6-8 weeks of age)were used. Mice were xenografted with LNCaP cells on their right flankby s.c. injection (8-10 million cells) in 100 μL growth medium and 100μL Matrigel (BD Matrigel™ Basement Membrane Matrix Growth FactorReduced, Phenol Red Free, Cat No 356231). Mice with established tumorshaving a diameter of at least ˜3 mm were included in the study anddivided into the three groups described below in Table 8. The animalswere i.v. injected in the tail vein. The 20 MBq activity-level waschosen because doses at this amount have been used in a study withm11B6, showing good therapeutic effect (see Example 7).

TABLE 8 Three groups of animals were included: One group injected with¹⁷⁷Lu-h11B6, one with ¹⁷⁷Lu-unsepcific mAb (to show the specificity ofh11B6), and one with NaCl (as a control group). Group n TreatmentActivity (MBq) 1 12 ¹⁷⁷Lu-h11B6 20 2 10 ¹⁷⁷Lu-unspecific mAb 20 3 10NaCl —

The therapeutic efficacy was assessed by repeated measurement of thetumour size using a caliper. The tumour volume was calculated bymeasuring the length (L) and the width (W) of the tumor and thencalculating the volume V as 0.5×L×W×W.

Also, hematological (white blood cell counts, red blood cell counts,platelet number and haemoglobin counts) and weight measurements weretaken repeatedly for all animals in order to identify any potentialhematological toxicity and to monitor the animals' general condition.The hematological toxicity is especially important to monitor whenevaluating radioimmunotherapy since the radioactivity will bedistributed in the blood and finally reach the bone marrow, where theblood stem cells are situated.

Mice that developed a tumour length/width exceeding 14 mm, or a weightloss exceeding 15% compared to the initial weight, or otherwise had anegatively affected general condition, or had a combination of all thesethree parameters, were terminated according to the ethical guidelines.

Results

Assessment of Therapeutic Efficacy

As shown in FIG. 14(a), administration of the exemplary humanised 11B6antibody of the invention (¹⁷⁷Lu-h11B6) prevented tumour growth in themice (and resulted in a pronounced reduction in tumour volume in all butone of the animals tested). In contrast, tumours continued to growquickly in mice treated with either the IgG control antibody (see FIG.14b ) or NaCl (see FIG. 14c ).

The data from the individual animals shown in FIG. 14 is summarized inthe form of Kaplan-Meier curves in FIG. 15. Administration of¹⁷⁷Lu-h11B6 produced a marked increase in the survival rate of the miceover the term of the experiment, with over 80% of the animals stillalive upon termination of the experiment 60 days post injection(compared to 0% survival in the two control groups).

Assessment of Hematological Toxicity

Assessment of white blood cell counts, red blood cell counts, plateletnumber, haemoglobin counts and weight did not reveal any toxicity effectof administration of ¹⁷⁷Lu-h11B6 (data not shown).

Discussion

The results of this study reveal a significant therapeutic effect of¹⁷⁷Lu-h11B6 treatment in the prostate cancer xenograft model.

The activity administered to the mico (20 MBq) corresponds to anabsorbed dose to the bone marrow of approximately 10 Gy, which waswell-tolerated by these animals. Even at this low activity of 20 MBq, alarge therapeutic effect was observed. As estimated earlier, a tumourabsorbed dose of at least 60 Gy can be expected.

No indications of hematological toxicity were observed.

REFERENCES

-   Almqvist Y., et al. In vitro and in vivo characterization of    177Lu-huA33: a radio-immunoconjugate against colorectal cancer. Nucl    Med Biol. 2006; 33:991-998.-   Pippin C G et al. Spectrophotometric method for the determination of    a bifunctional DTPA ligand in DTPA-monoclonal antibody conjugates.    Bioconjug Chem. 1992; 3:342-5.

Example 9—Radionuclide Therapy Dosimetry Planning and Treatment ofProstate Cancer in a Patient

For radionuclide therapy (RNT), the radiation source is distributed inthe whole and the radioactivity is normally administered systemically asa radiopharmaceutical. The radioactivity distribution depends on theamount of radiopharmaceutical that accumulates over time in differenttissues, something which varies between patients (1).

RNT treatment should be based on a prescribed absorbed dose (2). Thenfirst one should perform a pre-therapy study using a tracer amount ofthe radiopharmaceutical, and determine the tumor and organ absorbeddoses. Usually, this information is expressed as a factor describing theorgan absorbed dose per unit administered activity, in units of mGy/MBq;D^(P) _(T)(organ).

If the therapeutic administration is then given under similarconditions, this factor can be used to determine the activity that needsto be administered in order to deliver a prescribed absorbed dose to agiven organ, tissue or tumor (4,6).

In the case of prostate cancer treatment with radiolabelled h11B6antibodies, a pre-therapy study should be based on ¹¹¹In imaging with¹¹¹In-h11B6. ¹¹¹In is best suitable for quantitative (planar/SPECT)imaging when then ¹⁷⁷Lu is to be the therapeutic radionuclide. When thenthe D^(P) _(T)(organ) is determined the therapy can be given with atherapy activity A_(T) giving a prescribed therapy effect. Duringtherapy, the activity distribution and corresponding dose rate should becalculated based on imaging to get the actual therapy absorbed dosegiven to tumor and normal organs, necessary for evaluation of treatment.

In case of therapy where the bone marrow toxicity level is reached as aresult of the treatment planning then bone-marrow support is necessaryand based on dosimetry calculations for the bone marrow cavity the timefor reinfusion of stem cells has to be determined.

In summary, the following treatment scheme should be plannedaccordingly:

Pre-Therapy Dosimetry Study

-   1. 111 In-labeled h11B6 (200-300 MBq) injection-   2. Blood sampling—activity concentration in blood and plasma    determined first week.-   3. Imaging (SPECT/Planar) over 1 week (7 times)-   4. Organ Dosimetry based on LundaDose scheme (3)-   5. Therapy activity determined limited by specified absorbed dose to    radiosensitive organs as bone marrow (2-3 Gy), kidneys (20-30 Gy)    and liver (12-36 Gy).    Therapy Including Intra-Therapy Dosimetry-   1. 177Lu-labeled h11B6 administered (based on pretherapy dosimetry)-   2. Blood sampling—activity concentration in blood and plasma-   3. Imaging over 1 week (6 times)-   4. Organ Dosimetry=>Verification of prescribed therapy absorbed    dose.    Specific Comments on Dosimetry

The cumulated activity is the number of decays that occur in a givenregion over a period of time. The unit is Bq s, or Bq h. When ionizingradiation travels through matter, it interacts and deposits energy. Theenergy imparted is the sum of all energy deposits in a given volume. Theabsorbed dose is the ratio of the mean energy imparted and the mass ofthe volume. The unit of absorbed dose is Gray (Gy), 1 Gy equals 1 J/kg.

From the values of the activity in a tissue at different times, thecumulated activity is determined by integration, and the mean absorbeddose can be determined. Activity measurements are made using planarimaging for whole-organ dosimetry. Quantitative SPECT/CT allows fordosimetry in smaller volumes using voxel-based methods.

From the 3D distribution of activity concentration values, the absorbeddose rate distribution can be calculated using so-called point dosekernels or voxel S values, describing the energy deposition patternaround a point source located in water (or bone). This method assumesthat the anatomical region is homogeneous in terms of density, such assoft tissues within the trunk. For body regions where the density isheterogeneous, as in the lungs, a direct Monte Carlo calculation ispreferable. Here, the activity distribution from SPECT or PET is used asinput to a Monte Carlo dose calculation code.

REFERENCES

-   1. Strand S-E, Zanzonico P, Johnson T K. Pharmacokinetic modeling.    Med Phys 1993; 20(2):515-27-   2. ICRU report nr 67—Dose Specifications in Nuclear Medicine.    Adelstein S J, DeLuca P, Feinendegen L E, Green L, Howell R W, Humm    J L, Strand S E ICRU; 2002-   3. The LundADose Method for Planar Image Activity Quantification and    Absorbed-Dose Assessment in Radionuclide Therapy. Sjogreen, K.,    Ljungberg, M., Wingardh, K., Minarik, D., and Strand, S. E. (2005):    Cancer Biother. Radiopharm., 20:92-97-   4. Quantitative imaging for clinical dosimetry. Bardies M, Flux G,    Lassman M, Monsieurs N, Savolainen S, Strand S-E Nucl Instr and    Methods 2006:569:467-471.-   5. 177Lu-[DOTA0,Tyr3] octreotate therapy in patients with    disseminated neuroendocrine tumors: Analysis of dosimetry with    impact on future therapeutic strategy. Garkavij Michael, Nickel    Mattias, Sjögreen-Gleisner Katarina, Ljungberg Michael, Ohlsson    Tomas, Wingårdh Karin, Strand Sven-Erik, Tennvall Jan. Cancer    2010:116(4 Suppl):1084-92.-   6. Dosimetry in patients with B-cell lymphoma treated with    [(90)Y]ibritumomab tiuxetan or [(131)I]tositumomab Sjögreen-Gleisner    K., Dewaraja Y K., Chisea C., Tennvall J., Lind{tilde over (e)}n O.,    Strand S E, Ljungberg M. Q J Nucl Med Mol Imaging, 2011 April;    55(2):126-54.

The invention claimed is:
 1. An antibody polypeptide with bindingspecificity for human kallikrein-2 (hK2), wherein the antibodypolypeptide comprises (a) a heavy chain variable region comprising theamino acid sequences of SEQ ID NO:1 and SEQ ID NO:2 and SEQ ID NO:3; and(b) a light chain variable region comprising the amino acid sequences ofSEQ ID NO:4 and SEQ ID NO:5 and SEQ ID NO:6, wherein the heavy chainvariable region and light chain variable region comprise framework aminoacid sequences from one or more human antibodies, and wherein theantibody polypeptide is an intact IgG antibody.
 2. An antibodypolypeptide according to claim 1 wherein the antibody polypeptideexhibits an enhanced therapeutic ratio compared to the murine 11B6antibody.
 3. An antibody polypeptide according to claim 1 comprising aheavy chain variable region which comprises the amino acid sequence ofSEQ ID NO: 8 and a light chain variable region which comprises the aminoacid sequence of SEQ ID NO:
 9. 4. An antibody polypeptide according toclaim 1 comprising a heavy chain constant region which comprises theamino acid sequence of SEQ ID NO: 10 and a light chain constant regionwhich comprises the amino acid sequence of SEQ ID NO:
 11. 5. An antibodypolypeptide according to claim 1 comprising a heavy chain which consistsof the amino acid sequence of SEQ ID NO: 12 and a light chain whichconsists of the amino acid sequence of SEQ ID NO:
 13. 6. An antibodypolypeptide according to claim 1 wherein the antibody polypeptide islinked, directly or indirectly, to a therapeutic moiety.
 7. An antibodypolypeptide according to claim 6 wherein the therapeutic moiety is acytotoxic moiety that comprises one or more radioisotopes.
 8. Anantibody polypeptide according to claim 6 wherein the therapeutic moietyis a cytotoxic moiety that comprises one or more cytotoxic drugs.
 9. Anantibody polypeptide according to claim 1 wherein the antibodypolypeptide further comprises a detectable moiety.
 10. An antibodypolypeptide according to claim 9 wherein the detectable moiety comprisesa radioisotope.
 11. An antibody polypeptide according to claim 10wherein the radioisotope is capable of simultaneously acting in amulti-modal manner as a detectable moiety and also as a cytotoxicmoiety.
 12. A pharmaceutical composition comprising an antibodypolypeptide according to claim 1 and a pharmaceutically acceptableexcipient, diluent or carrier.
 13. A method for the treatment ordiagnosis of prostate cancer in a patient, the method comprising thestep of administering an effective amount of an antibody polypeptideaccording to claim
 1. 14. A method according to claim 13 wherein theprostate cancer to be treated is non-localised prostate cancer.
 15. Amethod according to claim 13 wherein the prostate cancer to be treatedis metastatic prostate cancer.
 16. A method according to claim 15wherein the metastatic prostate cancer to be treated is metastases ofthe lymph system; metastases of the bone; or metastasis within thepelvis, rectum, bladder or urethra.
 17. A method according to claim 13wherein the prostate cancer to be treated is castration-resistantprostate cancer (CRPC).
 18. A method according to claim 13 whereinradioguided surgery is performed on the patient following administrationof the antibody polypeptide in order to remove prostate cancer cells.